Add a new enum to differentiate between a complete decode and a
partial decode (with the third value being failure). Return this
value from SkImageDecoder::onDecode (in all subclasses, plus
SkImageDecoder_empty) and ::decode.
For convenience, if the enum is treated as a boolean, success and
partial success are both considered true.
Note that the static helper functions (DecodeFile etc) still return
true and false (for one thing, this allows us to continue to use
SkImageDecoder::DecodeMemory as an SkPicture::InstallPixelRefProc in
SkPicture::CreateFromStream).
Also correctly report failure in SkASTCImageDecoder::onDecode when
SkTextureCompressor::DecompressBufferFromFormat fails.
BUG=skia:3037
BUG:b/17419670
Review URL: https://codereview.chromium.org/647023006
Currently, the PDF backend does not support image filters (since PDF
does not have that functionality), so it simply removes them. This is
causing Chrome print preview to render incorrectly (see bug). The fix
here is to fall back to a raster device for image filters, as we used
to do in Blink. The resulting bitmap will be drawn to the destination
device as a normal main-memory-backed bitmap.
Note: this change invalidates the PDF results of all GMs containing
image filters (since they'll actually be rendered).
BUG=422144
Review URL: https://codereview.chromium.org/644323006
Reason for revert:
A large number of GMs on Ubuntu12 are failing. The text layout on GPU is visibly different than that for 8888.
Original issue's description:
> Change drawText() to generate positions and send to drawPosText()
>
> The idea here is to have a central place that does layout for drawText(), and
> then always feed text through drawPosText(). This both makes all of the
> GrTextContexts consistent in drawText() output, and does a better job of
> stressing drawPosText().
>
> Because of the effect of matrices on hinting and approximation error, the
> generated text is not 100% identical to that produced by the raster pipeline.
>
> BUG=skia:2778
>
> Committed: https://skia.googlesource.com/skia/+/7851a56895c9c076f73a835a7dd51d3c6180c16fTBR=cdalton.nvidia@gmail.com,bungeman@google.com,reed@google.com
NOTREECHECKS=true
NOTRY=true
BUG=skia:2778
Review URL: https://codereview.chromium.org/659993003
The idea here is to have a central place that does layout for drawText(), and
then always feed text through drawPosText(). This both makes all of the
GrTextContexts consistent in drawText() output, and does a better job of
stressing drawPosText().
Because of the effect of matrices on hinting and approximation error, the
generated text is not 100% identical to that produced by the raster pipeline.
BUG=skia:2778
Review URL: https://codereview.chromium.org/653133004
Refactor SkGLContext to be actually extendable. Before, non-trivial subclass
would need to destroy the GL connection upon running the destructor. However,
the base class would run GL commands in its own destructor (with destroyed GL
connection)
Refactor so that SkGLContext subclass object creation is completely done by
the factory function. If the factory function returns a non-NULL ptr, it means the context
is usable.
The destruction is done with the destructor instead of virtual function called
upon destruction. Make the destructors not to call virtual functions, for
clarity.
Remove custom 1x1 FBO setup code from the base class. It appears not to be used
anymore.
BUG=skia:2992
Review URL: https://codereview.chromium.org/640283004
A careful reading of the preprocessor specification indicates that
any use of the 'defined' operator outside the form of 'defined X' or
'defined ( X )' directly in the constant expression of a '#if' or
'#elif' may cause undefined behavior.
In particular, msvc is very unpredictable. The 'defined X' and
'defined ( X )' forms behave differently when created from marco
expansion, with 'defined ( X )' generally evaluating to '0L'. The
'defined X' form generally behaves more the way one would expect,
but still has a number of quirks which should simply be considered
undefined behavior.
BUG=chromium:419245
Review URL: https://codereview.chromium.org/657183002
Function- or method- local scope isn't threadsafe; the pointer is generally
zero-initialized on first use in function scope (i.e. lazily... we have to go
deeper), but for globals we can be pretty sure the linker will do that for us.
BUG=skia:
No public API changes.
TBR=reed@google.com
Review URL: https://codereview.chromium.org/651723003
Consolidate read/write funcs in context.
Remove support for reading pixels from a surface that's not a target. It's currently broken and neither used nor tested.
Review URL: https://codereview.chromium.org/648863002
Reason for revert:
Crashing the Windows bots.
Original issue's description:
> Fix color emoji.
>
> Removes the GrMaskFormat and single atlas in GrTextStrike.
> Replaces it by storing the GrMaskFormat in each GrGlyph, and
> doing a lookup for the correct atlas based on that.
>
> Disables color glyph rendering in GrDistanceFieldTextContext
> for now.
>
> BUG=skia:2887
>
> Committed: https://skia.googlesource.com/skia/+/bc92163ddfe957ad6ffbb02ac40e0ba75ff82216TBR=robertphillips@google.com,bungeman@google.com,reed@google.com,bsalomon@google.com
NOTREECHECKS=true
NOTRY=true
BUG=skia:2887
Review URL: https://codereview.chromium.org/640413004
Removes the GrMaskFormat and single atlas in GrTextStrike.
Replaces it by storing the GrMaskFormat in each GrGlyph, and
doing a lookup for the correct atlas based on that.
Disables color glyph rendering in GrDistanceFieldTextContext
for now.
BUG=skia:2887
Review URL: https://codereview.chromium.org/636183005
Before getting too far into changing how SkTileGrid stores its tiles, I figured I'd
better see how much I can tweak out the existing format. Cleverly, that way
any improvements I make by changing the format will look that much less
impressive.
This CL looks like it will be a 5-15% win in time spent recording, with no effect
on playback.
This CL also shrinks the tiles to fit exactly when we're done inserting,
using newly added SkTDArray::shrinkToFit(). It's quite cheap to run (maybe
taking back 1-2% from those 5-15% wins), and means we'll lug around about 15%
fewer bytes in the tile grids. Note though this strategy temporarily uses up to
30% more memory while building the tile grid. For our largest SKPs, that's
maybe 75-100K extra.
BUG=skia:
Committed: https://skia.googlesource.com/skia/+/52455cbc02d7f480d988ae7cdacc11ad69078c2c
CQ_EXTRA_TRYBOTS=tryserver.skia:Canary-Chrome-Ubuntu13.10-Ninja-x86_64-ToT-Trybot
Review URL: https://codereview.chromium.org/639823005
Reason for revert:
failed assertion "fXTiles * fYTiles != 0"
Original issue's description:
> Use BBH reserve hook to preallocate space for tiles.
>
> Before getting too far into changing how SkTileGrid stores its tiles, I figured I'd
> better see how much I can tweak out the existing format. Cleverly, that way
> any improvements I make by changing the format will look that much less
> impressive.
>
> This CL looks like it will be a 5-15% win in time spent recording, with no effect
> on playback.
>
> This CL also shrinks the tiles to fit exactly when we're done inserting,
> using newly added SkTDArray::shrinkToFit(). It's quite cheap to run (maybe
> taking back 1-2% from those 5-15% wins), and means we'll lug around about 15%
> fewer bytes in the tile grids. Note though this strategy temporarily uses up to
> 30% more memory while building the tile grid. For our largest SKPs, that's
> maybe 75-100K extra.
>
> BUG=skia:
>
> Committed: https://skia.googlesource.com/skia/+/52455cbc02d7f480d988ae7cdacc11ad69078c2cTBR=reed@google.com,robertphillips@google.com,mtklein@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=skia:
Review URL: https://codereview.chromium.org/642933002
Before getting too far into changing how SkTileGrid stores its tiles, I figured I'd
better see how much I can tweak out the existing format. Cleverly, that way
any improvements I make by changing the format will look that much less
impressive.
This CL looks like it will be a 5-15% win in time spent recording, with no effect
on playback.
This CL also shrinks the tiles to fit exactly when we're done inserting,
using newly added SkTDArray::shrinkToFit(). It's quite cheap to run (maybe
taking back 1-2% from those 5-15% wins), and means we'll lug around about 15%
fewer bytes in the tile grids. Note though this strategy temporarily uses up to
30% more memory while building the tile grid. For our largest SKPs, that's
maybe 75-100K extra.
BUG=skia:
Review URL: https://codereview.chromium.org/639823005
Make the Sk GL context class, SkGLNativeContext, an abstract base class. Before,
it depended on ifdefs to implement the platform dependent polymorphism. Move
the logic to subclasses of the various platform implementations.
This a step to enable Skia embedders to compile dm and bench_pictures. The
concrete goal is to support running these test apps with Chromium command buffer.
With this change, Chromium can implement its own version of SkGLNativeContext
that uses command buffer, and host the implementation in its own repository.
Implements the above by renaming the SkGLContextHelper to SkGLContext and
removing the unneeded SkGLNativeContext. Also removes
SkGLNativeContext::AutoRestoreContext functionality, it appeared to be unused:
no use in Skia code, and no tests.
BUG=skia:2992
Committed: https://skia.googlesource.com/skia/+/a90ed4e83897b45d6331ee4c54e1edd4054de9a8
Review URL: https://codereview.chromium.org/630843002
Reason for revert:
nanobech failing on Android
Original issue's description:
> Make the Sk GL context class an abstract base class
>
> Make the Sk GL context class, SkGLNativeContext, an abstract base class. Before,
> it depended on ifdefs to implement the platform dependent polymorphism. Move
> the logic to subclasses of the various platform implementations.
>
> This a step to enable Skia embedders to compile dm and bench_pictures. The
> concrete goal is to support running these test apps with Chromium command buffer.
>
> With this change, Chromium can implement its own version of SkGLNativeContext
> that uses command buffer, and host the implementation in its own repository.
>
> Implements the above by renaming the SkGLContextHelper to SkGLContext and
> removing the unneeded SkGLNativeContext. Also removes
> SkGLNativeContext::AutoRestoreContext functionality, it appeared to be unused:
> no use in Skia code, and no tests.
>
> BUG=skia:2992
>
> Committed: https://skia.googlesource.com/skia/+/a90ed4e83897b45d6331ee4c54e1edd4054de9a8TBR=kkinnunen@nvidia.com
NOTREECHECKS=true
NOTRY=true
BUG=skia:2992
Review URL: https://codereview.chromium.org/639793002
Make the Sk GL context class, SkGLNativeContext, an abstract base class. Before,
it depended on ifdefs to implement the platform dependent polymorphism. Move
the logic to subclasses of the various platform implementations.
This a step to enable Skia embedders to compile dm and bench_pictures. The
concrete goal is to support running these test apps with Chromium command buffer.
With this change, Chromium can implement its own version of SkGLNativeContext
that uses command buffer, and host the implementation in its own repository.
Implements the above by renaming the SkGLContextHelper to SkGLContext and
removing the unneeded SkGLNativeContext. Also removes
SkGLNativeContext::AutoRestoreContext functionality, it appeared to be unused:
no use in Skia code, and no tests.
BUG=skia:2992
Review URL: https://codereview.chromium.org/630843002
this is a huge refactor and cleanup of the gl shader building system in
Skia. The entire shader building pipeline is now part of
GrGLProgramCreator, which takes a gp, and some fps, and creates a
program. I added some subclasses of GrGLProgram to handle the
eccentricities of Nvpr/Nvpres. Outside of the builders folder
and GrGLPrograms, this change is basically just a rename
solo gp
BUG=skia:
Committed: https://skia.googlesource.com/skia/+/fe1233c3f12f81bb675718516bbb32f72af726ec
Review URL: https://codereview.chromium.org/611653002
Reason for revert:
Seems to have messed up windows 7 gms
Original issue's description:
> Cleanup of shader building system
>
> this is a huge refactor and cleanup of the gl shader building system in
> Skia. The entire shader building pipeline is now part of
> GrGLProgramCreator, which takes a gp, and some fps, and creates a
> program. I added some subclasses of GrGLProgram to handle the
> eccentricities of Nvpr/Nvpres. Outside of the builders folder
> and GrGLPrograms, this change is basically just a rename
>
>
> solo gp
>
> BUG=skia:
>
> Committed: https://skia.googlesource.com/skia/+/fe1233c3f12f81bb675718516bbb32f72af726ecTBR=bsalomon@google.com
NOTREECHECKS=true
NOTRY=true
BUG=skia:
Review URL: https://codereview.chromium.org/635533005
this is a huge refactor and cleanup of the gl shader building system in
Skia. The entire shader building pipeline is now part of
GrGLProgramCreator, which takes a gp, and some fps, and creates a
program. I added some subclasses of GrGLProgram to handle the
eccentricities of Nvpr/Nvpres. Outside of the builders folder
and GrGLPrograms, this change is basically just a rename
solo gp
BUG=skia:
Review URL: https://codereview.chromium.org/611653002
Drop ref on GrGpuResources when GrProgramElement loses its last ref and already has a pending execution.
BUG=skia:2889
Review URL: https://codereview.chromium.org/612293003
Reason for revert:
Changing some GMs
Original issue's description:
> Add isSingleComponent bool to getConstantColorComponent
>
> Initial step to allowing effects to use/output 1 or 4 color/coverage components. This cl doesn't change any current logic and all effects still assume they are working with 4 components.
>
> BUG=skia:
>
> Committed: https://skia.googlesource.com/skia/+/3b8af078281a5a20f951b9fd84f38d92b8f6217bTBR=joshualitt@chromium.org,bsalomon@google.com,reed@google.com,egdaniel@google.com
NOTREECHECKS=true
NOTRY=true
BUG=skia:
Review URL: https://codereview.chromium.org/617853003
Initial step to allowing effects to use/output 1 or 4 color/coverage components. This cl doesn't change any current logic and all effects still assume they are working with 4 components.
BUG=skia:
Review URL: https://codereview.chromium.org/608253002
This removes:
1) ability to record old pictures with SkPictureRecorder;
2) a couple tests specific to the old backend.
The functionality of DEPRECATED_beginRecording() now lives in
(private) SkPicture::Backport(), which is the only place we
need it now.
BUG=skia:
TBR=reed@google.com
Review URL: https://codereview.chromium.org/618303002
Having hoisted layers from different pictures invalidates the assumptions of the old GrReplacements object. This is fixed by switching to a SkTDynamicHash-based back-end.
Sub-picture-layers also require that the replacement drawing occur for the sub-pictures too. The ReplaceDraw object is added to make this happen and limit the replacement lookup to saveLayer draw commands.
This is split out of (Fix sub-picture layer rendering bugs - https://codereview.chromium.org/597293002/).
BUG=skia:2315
Review URL: https://codereview.chromium.org/607763008
Feature-wise, this removes:
1) BBH support;
2) peephole optimizations;
3) record-time text op specializations;
4) the guarantee that SkPaints are flattened.
This deletes the optimizations GM, which only exists to test the peepholes of
the old backend. SkRecord optimizations are unit tested, and if that ever fails we
can think about adding another GM like this, but they're different enough we'd
want to start from scratch anyway.
We need to keep the code that plays back the specialized text ops around for
a while for compatibility with existing .SKPs that have those ops recorded.
BUG=skia:
CQ_EXTRA_TRYBOTS=tryserver.skia:Canary-Chrome-Ubuntu13.10-Ninja-x86_64-ToT-Trybot
R=robertphillips@google.com, reed@google.com, mtklein@google.com
Author: mtklein@chromium.org
Review URL: https://codereview.chromium.org/617953002
Implement proper x/y drawTextBlob() handling by plumbing a
drawPosText() offset parameter (to act as an additional glyph pos
translation) throughout the device layer.
The new offset superceeds the existing constY, with a minor semantic
tweak: whereas previous implementations were ignoring constY in 2D
positioning mode (scalarsPerGlyph == 2), now the offset is always
observed, in all positioning modes. We can do this because existing
drawPosText() clients always pass constY == 0 for full positioning mode.
R=reed@google.com, jvanverth@google.com, robertphillips@google.com
Review URL: https://codereview.chromium.org/605533002
fDirtyBits is only used by SkPaint::FlatteningTraits, which in turn was
only used as a smaller, faster format to flatten paints in-memory to dedup
them in the old picture backend.
SkRecord obsoleted all this. Neither flatten()/unflatten() (disk format)
nor FlatteningTraits is used anywhere performance or size matters.
Here I revert the deduping code back to using the disk format for flattened paints.
We stil do have to flatten and unflatten paints while coverting from SkRecord
backend to the old backend, so we can't just delete this all yet, but any
faithful round trip flatten()/unflatten() pair will be fine, however slow.
NOTRY=true
BUG=skia:
R=reed@google.com, mtklein@google.com
Author: mtklein@chromium.org
Review URL: https://codereview.chromium.org/604813003
Refactored text blob backend for improved performance: instead of using
separate buffers for runs/positions/glyphs, everything is now packed in
a consolidated slab (including the SkTextBlob object itself!).
Benefits:
* number of allocations per blob construction reduced from ~4 to 1
(also minimizes internal fragmentation)
* run record size reduced by 8 bytes
This takes the blob construction overhead down to negligible levels
(for the current Blink uncached textblob implementation).
Unfortunately, the code is much more finicky (run merging in
particular) -- hence the assert spree.
Multi-run blobs are vulnerable to realloc storms but this is not a
problem at the moment because Blink is using one-run blobs 99% of the
time. Will be addressed in the future.
R=mtklein@google.com, reed@google.com, robertphillips@google.com
Committed: https://skia.googlesource.com/skia/+/13645ea0ea87038ebd71be3bd6d53b313069a9e4
Author: fmalita@chromium.org
Review URL: https://codereview.chromium.org/581173003
Reason for revert:
Broke the new blobshader gm.
Original issue's description:
> Souped-up SkTextBlob.
>
> Refactored text blob backend for improved performance: instead of using
> separate buffers for runs/positions/glyphs, everything is now packed in
> a consolidated slab (including the SkTextBlob object itself!).
>
> Benefits:
>
> * number of allocations per blob construction reduced from ~4 to 1
> (also minimizes internal fragmentation)
> * run record size reduced by 8 bytes
>
> This takes the blob construction overhead down to negligible levels
> (for the current Blink uncached textblob implementation).
>
> Unfortunately, the code is much more finicky (run merging in
> particular) -- hence the assert spree.
>
> Multi-run blobs are vulnerable to realloc storms but this is not a
> problem at the moment because Blink is using one-run blobs 99% of the
> time. Will be addressed in the future.
>
>
> R=reed@google.com,mtklein@google.com,robertphillips@google.com
>
> Committed: https://skia.googlesource.com/skia/+/13645ea0ea87038ebd71be3bd6d53b313069a9e4R=mtklein@google.com, reed@google.com, robertphillips@google.comTBR=mtklein@google.com, reed@google.com, robertphillips@google.com
NOTREECHECKS=true
NOTRY=true
Author: fmalita@chromium.org
Review URL: https://codereview.chromium.org/588853002
Refactored text blob backend for improved performance: instead of using
separate buffers for runs/positions/glyphs, everything is now packed in
a consolidated slab (including the SkTextBlob object itself!).
Benefits:
* number of allocations per blob construction reduced from ~4 to 1
(also minimizes internal fragmentation)
* run record size reduced by 8 bytes
This takes the blob construction overhead down to negligible levels
(for the current Blink uncached textblob implementation).
Unfortunately, the code is much more finicky (run merging in
particular) -- hence the assert spree.
Multi-run blobs are vulnerable to realloc storms but this is not a
problem at the moment because Blink is using one-run blobs 99% of the
time. Will be addressed in the future.
R=mtklein@google.com, reed@google.com, robertphillips@google.com
Author: fmalita@chromium.org
Review URL: https://codereview.chromium.org/581173003
typeface. Loads the paths using the driver's glyph loading routines.
Refactors GrPathRange to accept a PathGenerator class that it uses to
lazily initialize its paths. The client code is no longer expected to
initialize the paths in a GrPathRange; instead it must provide a
PathGenerator* instance to createPathRange().
Adds a new createGlyphs() method to GrPathRendering that creates a
range of glyph paths, indexed by glyph id. GrPathRendering implements
createGlyphs() with a PathGenerator that loads glyph paths using the
skia frameworks. GrGLPathRendering uses glMemoryGlyphIndexArrayNV()
instead, when possible, to load the glyph paths.
Removes all GlyphPathRange logic from GrStencilAndCoverTextContext.
It instead uses createGlyphs().
BUG=skia:2939
R=bsalomon@google.com, jvanverth@google.com
Author: cdalton@nvidia.com
Review URL: https://codereview.chromium.org/563283004
blink skips all pending commands during picture recording if it is drawing an opaque full-frame
geometry or image. This may improve performance for some edge cases. To recognize an opaque
full-frame drawing should be cheap enough. Otherwise, the overhead will offset the improvement.
Unfortunately, data from perf for content_shell on Nexus7 shows that SkDeferredCanvas::isFullFrame
is far from cheap. Table below shows that how much isFullFrame() costs in the whole render process.
benchmark percentage
my local benchmark(draw 1000 sprites) 4.1%
speedReading 2.8%
FishIETank(1000 fishes) 1.5%
GUIMark3 Bitmap 2.0%
By contrast, real recording (SkGPipeCanvas::drawBitmapRectToRect) and real rasterization
(GrDrawTarget::drawRect) cost ~4% and ~6% in the whole render process respectively. Apparently,
SkDeferredCanvas::isFullFrame() is nontrivial.
getDeviceSize() is the main contributor to this hotspot. The change simply save the canvasSize and
reuse it among drawings if it is not a fresh frame. This change cut off ~65% (or improved ~2 times)
of isFullFrame().
telemetry smoothness canvas_tough_test didn't show obvious improvement or regression.
BUG=411166
Committed: https://skia.googlesource.com/skia/+/8e45c3777d886ba3fe239bb549d06b0693692152R=junov@chromium.org, tomhudson@google.com, reed@google.com
Author: yunchao.he@intel.com
Review URL: https://codereview.chromium.org/545813002
Reason for revert:
This is leaking memory:
http://108.170.220.120:10117/builders/Test-Ubuntu13.10-GCE-NoGPU-x86_64-Debug-ASAN/builds/2516/steps/RunDM/logs/stdio
Original issue's description:
> Picture Recording: fix the performance bottleneck in SkDeferredCanvas::isFullFrame
>
> blink skips all pending commands during picture recording if it is drawing an opaque full-frame
> geometry or image. This may improve performance for some edge cases. To recognize an opaque
> full-frame drawing should be cheap enough. Otherwise, the overhead will offset the improvement.
> Unfortunately, data from perf for content_shell on Nexus7 shows that SkDeferredCanvas::isFullFrame
> is far from cheap. Table below shows that how much isFullFrame() costs in the whole render process.
>
> benchmark percentage
> my local benchmark(draw 1000 sprites) 4.1%
> speedReading 2.8%
> FishIETank(1000 fishes) 1.5%
> GUIMark3 Bitmap 2.0%
>
> By contrast, real recording (SkGPipeCanvas::drawBitmapRectToRect) and real rasterization
> (GrDrawTarget::drawRect) cost ~4% and ~6% in the whole render process respectively. Apparently,
> SkDeferredCanvas::isFullFrame() is nontrivial.
>
> getDeviceSize() is the main contributor to this hotspot. The change simply save the canvasSize and
> reuse it among drawings if it is not a fresh frame. This change cut off ~65% (or improved ~2 times)
> of isFullFrame().
>
> telemetry smoothness canvas_tough_test didn't show obvious improvement or regression.
>
> BUG=411166
>
> Committed: https://skia.googlesource.com/skia/+/8e45c3777d886ba3fe239bb549d06b0693692152R=junov@chromium.org, tomhudson@google.com, reed@google.com, yunchao.he@intel.comTBR=junov@chromium.org, reed@google.com, tomhudson@google.com, yunchao.he@intel.com
NOTREECHECKS=true
NOTRY=true
BUG=411166
Author: mtklein@google.com
Review URL: https://codereview.chromium.org/571053002
blink skips all pending commands during picture recording if it is drawing an opaque full-frame
geometry or image. This may improve performance for some edge cases. To recognize an opaque
full-frame drawing should be cheap enough. Otherwise, the overhead will offset the improvement.
Unfortunately, data from perf for content_shell on Nexus7 shows that SkDeferredCanvas::isFullFrame
is far from cheap. Table below shows that how much isFullFrame() costs in the whole render process.
benchmark percentage
my local benchmark(draw 1000 sprites) 4.1%
speedReading 2.8%
FishIETank(1000 fishes) 1.5%
GUIMark3 Bitmap 2.0%
By contrast, real recording (SkGPipeCanvas::drawBitmapRectToRect) and real rasterization
(GrDrawTarget::drawRect) cost ~4% and ~6% in the whole render process respectively. Apparently,
SkDeferredCanvas::isFullFrame() is nontrivial.
getDeviceSize() is the main contributor to this hotspot. The change simply save the canvasSize and
reuse it among drawings if it is not a fresh frame. This change cut off ~65% (or improved ~2 times)
of isFullFrame().
telemetry smoothness canvas_tough_test didn't show obvious improvement or regression.
BUG=411166
R=junov@chromium.org, tomhudson@google.com, reed@google.com
Author: yunchao.he@intel.com
Review URL: https://codereview.chromium.org/545813002
