I don't really expect this to fix the errors, but I think
it's worth it to try shaking up the valgrind bot overnight.
There's some strange behavior with regard to color type on
the valgrind bot that I can't reproduce and that we aren't
seeing on any of the other bots.
TBR=mtklein,scroggo
BUG=skia:
Review URL: https://codereview.chromium.org/1418723002
- Remove --images '' to renable image benchmarking
- Add a flag to disable testing JPEG's buildTileIndex, since it also leaks memory
- Do not run images on GPU
- Do not run large interlaced images on 32 bit bots
- When buildTileIndex is not being used in the subset benches, do not use it for BRD
BUG=skia:3418
BUG=skia:4469
BUG=skia:4471
BUG=skia:4360
Review URL: https://codereview.chromium.org/1396113002
Instead of decoding one line at a time, if the ScanlineOrder is kNone,
decode all of the lines in one pass, and then copy the subset into the
output. This will allow us to more realistically test subset decodes
for interlaced png. It also makes running them not take forever.
Do *not* support other modes (besides kTopDown), since they are not
used by the big three we need to replace BitmapRegionDecoder
implementation (skbug.com/4428).
Fix a bug in SubsetTranslateBench and SubsetZoomBench:
When we decode another subset, we need to reset the scanline decode
first. This bug appears to have been present since the introduction of
these tests in crrev.com/1160953002
BUG=skia:4205
BUG=skia:3418
Review URL: https://codereview.chromium.org/1387233002
GLBenches do not expect gl state to change between onPerCanvasPreDraw and *PostDraw, but we do a clear and sometimes we clear as draw. This causes us to bind vertex objects / programs / etc.
This change creates two new virtual methods which are called right before and immediately after timing.
BUG=skia:
Review URL: https://codereview.chromium.org/1379853003
Benefits:
- This mimics other decoding APIs (including the ones SkCodec relies
on, e.g. a png_struct, which can be used to decode an entire image or
one line at a time).
- It allows a client to ask us to do what we can do efficiently - i.e.
start from encoded data and either decode the whole thing or scanlines.
- It removes the duplicate methods which appeared in both SkCodec and
SkScanlineDecoder (some of which, e.g. in SkJpegScanlineDecoder, just
call fCodec->sameMethod()).
- It simplifies moving more checks into the base class (e.g. the
examples in skbug.com/4284).
BUG=skia:4175
BUG=skia:4284
=====================================================================
SkScanlineDecoder.h/.cpp:
Removed.
SkCodec.h/.cpp:
Add methods, enums, and variables which were previously in
SkScanlineDecoder.
Default fCurrScanline to -1, as a sentinel that start has not been
called.
General changes:
Convert SkScanlineDecoders to SkCodecs.
General changes in SkCodec subclasses:
Merge SkScanlineDecoder implementation into SkCodec. Most (all?) owned
an SkCodec, so they now call this-> instead of fCodec->.
SkBmpCodec.h/.cpp:
Replace the unused rowOrder method with an override for
onGetScanlineOrder.
Make getDstRow const, since it is called by onGetY, which is const.
SkCodec_libpng.h/.cpp:
Make SkPngCodec an abstract class, with two subclasses which handle
scanline decoding separately (they share code for decoding the entire
image). Reimplement onReallyHasAlpha so that it can return the most
recent result (e.g. after a scanline decode which only decoded part
of the image) or a better answer (e.g. if the whole image is known to
be opaque).
Compute fNumberPasses early, so we know which subclass to instantiate.
Make SkPngInterlaceScanlineDecoder use the base class' fCurrScanline
rather than a separate variable.
CodexTest.cpp:
Add tests for the state changes in SkCodec (need to call start before
decoding scanlines; calling getPixels means that start will need to
be called again before decoding more scanlines).
Add a test which decodes in stripes, currently only used for an
interlaced PNG.
TODO: Add tests for onReallyHasAlpha.
Review URL: https://codereview.chromium.org/1365313002
SkBitmapRegionDecoderInterface provides an interface
for multiple implementations of Android's
BitmapRegionDecoder.
We already have correctness tests in DM that will enable us
to compare the quality of our various BRD implementations.
We also need these performance tests to compare the speed
of our various implementations.
BUG=skia:4357
Review URL: https://codereview.chromium.org/1344993003
Unfortunately, immintrin.h (which is also included by SkTypes)
includes xmmintrin.h which includes mm_malloc.h which includes
stdlib.h for malloc even though, from the implementation, it is
difficult to see why.
Fortunately, arm_neon.h does not seem to be involved in such
shenanigans, so building for Android will keep things sane.
TBR=reed@google.com
Doesn't change Skia API, just moves an include.
Review URL: https://codereview.chromium.org/1313203003
Prior to this CL, if a client wanted to decode scanlines, they had to
create an SkCodec in order to get an SkScanlineDecoder. This introduces
complications if input data is not easily shared between the two
objects.
Instead, add methods to SkScanlineDecoder for creating a new one from
input data, and remove the creation functions from SkCodec.
Update DM and tests.
Review URL: https://codereview.chromium.org/1267583002
Make getScanlineDecoder return a new object each time, which is
owned by the caller, and independent from any existing scanline
decoders and the SkCodec itself.
Since the SkCodec already contains the entire state machine, and it
is used by the scanline decoders, simply create a new SkCodec which
is now owned by the scanline decoder.
Move code that cleans up after using a scanline decoder into its
destructor
One side effect is that creating the first scanline decoder requires
a duplication of the stream and re-reading the header. (With some
more complexity/changes, we could pass the state machine to the
scanline decoder and make the SkCodec recreate its own state machine
instead.) The typical client of the scanline decoder (region decoder)
uses an SkMemoryStream, so the duplication is cheap, although we
should consider the extra time to reread the header/recreate the state
machine. (If/when we use the scanline decoder for other purposes,
where the stream may not be cheaply duplicated, we should consider
passing the state machine.)
One (intended) result of this change is that a client can create a
new scanline decoder in a new thread, and decode different pieces of
the image simultaneously.
In SkPngCodec::decodePalette, use fBitDepth rather than a parameter.
Review URL: https://codereview.chromium.org/1230033004
SkImageGenerator makes some assumptions that are not necessarily valid
for SkCodec. For example, SkCodec does not assume that it can always be
rewound.
We also have an ongoing question of what an SkCodec should report as
its default settings (i.e. the return from getInfo). It makes sense for
an SkCodec to report that its pixels are unpremultiplied, if that is
the case for the underlying data, but if a client of SkImageGenerator
uses the default settings (as many do), they will receive
unpremultiplied pixels which cannot (currently) be drawn with Skia. We
may ultimately decide to revisit SkCodec reporting an SkImageInfo, but
I have left it unchanged for now.
Import features of SkImageGenerator used by SkCodec into SkCodec.
I have left SkImageGenerator unchanged for now, but it no longer needs
Result or Options. This will require changes to Chromium.
Manually handle the lifetime of fScanlineDecoder, so SkScanlineDecoder.h
can include SkCodec.h (where Result is), and SkCodec.h does not need
to include it (to delete fScanlineDecoder).
In many places, make the following simple changes:
- Now include SkScanlineDecoder.h, which is no longer included by
SkCodec.h
- Use the enums in SkCodec, rather than SkImageGenerator
- Stop including SkImageGenerator.h where no longer needed
Review URL: https://codereview.chromium.org/1220733013
Changes verbose mode to print both the table and the individual sample
values. No need to hold back information in verbose mode.
BUG=skia:
Review URL: https://codereview.chromium.org/1208763003
Adds a nanobench mode that takes samples for a fixed amount of time,
rather than taking a fixed amount of samples.
BUG=skia:
Review URL: https://codereview.chromium.org/1204153002
Improves the GPU measuring accuracy of nanobench by using fence syncs.
Fence syncs are very widely supported and available on almost every
platform.
NO_MERGE_BUILDS
BUG=skia:
Review URL: https://codereview.chromium.org/1194783003
I think these changes to the subset benchmarks cover what we discussed yesterday.
I removed the divisor benchmarks (2x2, 3x3) and changed the single subset benchmarks.
Also, we will no longer benchmark subset decodes on small images.
BUG=skia:
Review URL: https://codereview.chromium.org/1188223002
This makes it easier to benchmark _mpd variants in a profiler.
E.g.,
<profiler> out/Release/nanobench --images --config 8888 --loops -1 --match sp_desk_nytimes
BUG=skia:
Review URL: https://codereview.chromium.org/1184673006
Now that all SkCodecs can rewind (assuming the stream is rewindable),
we do not need to special case it.
Pointed out by Derek in the code review that added this.
TBR=djsollen
Review URL: https://codereview.chromium.org/1058633002
CodecBench:
Add new class for timing using SkCodec.
DecodingBench:
Include creating a decoder inside the loop. This is to have a better
comparison against SkCodec. SkCodec's factory function does not
necessarily read the same amount as SkImageDecoder's, so in order to
have a meaningful comparison, read the entire stream from the
beginning. Also for comparison, create a new SkStream from the
SkData each time.
Add a debugging check to make sure we have an SkImageDecoder.
Add include guards.
nanobench.cpp:
Decode using SkCodec.
When decoding using SkImageDecoder, exclude benches where we decoded
to a different color type than requested. SkImageDecoder may decide to
decode to a different type, in which case the name is misleading.
TODOs:
Now that we ignore color types that do not match the desired
color type, we should add Index8. This also means calling the more
complex version of getPixels so CodecBench can support kIndex8.
BUG=skia:3257
Review URL: https://codereview.chromium.org/1044363002
Seems strictly more useful.
This implements Mac and Windows, which seemed easy. Don't know how to do this on Linux yet.
BUG=skia:
CQ_EXTRA_TRYBOTS=client.skia:Test-Mac10.9-MacMini6.2-HD4000-x86_64-Debug-Trybot
NOTREECHECKS=true
TBR=halcanary@google.com
Review URL: https://codereview.chromium.org/990723002
This basically takes out the Windows-only hacks and promotes them to
cross-platform behavior driven by --gpu_threading.
- When --gpu_threading is false (the default), this puts GPU tasks and tests
together in the same GPU enclave. They all run serially.
- When --gpu_threading is true, both the tests and the tasks run totally
independently, just like the thread-safe CPU-bound work.
BUG=skia:3255
Review URL: https://codereview.chromium.org/847273005
SkStream is a stateful object, so it does not make sense for it to have
multiple owners. Make SkStream inherit directly from SkNoncopyable.
Update methods which previously called SkStream::ref() (e.g.
SkImageDecoder::buildTileIndex() and SkFrontBufferedStream::Create(),
which required the existing owners to call SkStream::unref()) to take
ownership of their SkStream parameters and delete when done (including
on failure).
Switch all SkAutoTUnref<SkStream>s to SkAutoTDelete<SkStream>s. In some
cases this means heap allocating streams that were previously stack
allocated.
Respect ownership rules of SkTypeface::CreateFromStream() and
SkImageDecoder::buildTileIndex().
Update the comments for exceptional methods which do not affect the
ownership of their SkStream parameters (e.g.
SkPicture::CreateFromStream() and SkTypeface::Deserialize()) to be
explicit about ownership.
Remove test_stream_life, which tested that buildTileIndex() behaved
correctly when SkStream was a ref counted object. The test does not
make sense now that it is not.
In SkPDFStream, remove the SkMemoryStream member. Instead of using it,
create a new SkMemoryStream to pass to fDataStream (which is now an
SkAutoTDelete).
Make other pdf rasterizers behave like SkPDFDocumentToBitmap.
SkPDFDocumentToBitmap delete the SkStream, so do the same in the
following pdf rasterizers:
SkPopplerRasterizePDF
SkNativeRasterizePDF
SkNoRasterizePDF
Requires a change to Android, which currently treats SkStreams as ref
counted objects.
Review URL: https://codereview.chromium.org/849103004
Restructure SkGpuDevice creation:
*SkSurfaceProps are optional.
*Use SkSurfaceProps to communicate DF text rather than a flag.
*Tell SkGpuDevice::Create whether RT comes from cache or not.
Review URL: https://codereview.chromium.org/848903004
BUG=skia:3255
I think this supports everything DM used to, but has completely refactored how
it works to fit the design in the bug.
Configs like "tiles-gpu" are automatically wired up.
I wouldn't suggest looking at this as a diff. There's just a bunch of deleted
files, a few new files, and one new file that shares a name with a deleted file
(DM.cpp).
NOTREECHECKS=true
Committed: https://skia.googlesource.com/skia/+/709d2c3e5062c5b57f91273bfc11a751f5b2bb88
Review URL: https://codereview.chromium.org/788243008
Reason for revert:
plenty of data
Original issue's description:
> Sketch DM refactor.
>
> BUG=skia:3255
>
>
> I think this supports everything DM used to, but has completely refactored how
> it works to fit the design in the bug.
>
> Configs like "tiles-gpu" are automatically wired up.
>
> I wouldn't suggest looking at this as a diff. There's just a bunch of deleted
> files, a few new files, and one new file that shares a name with a deleted file
> (DM.cpp).
>
> NOTREECHECKS=true
>
> Committed: https://skia.googlesource.com/skia/+/709d2c3e5062c5b57f91273bfc11a751f5b2bb88TBR=bsalomon@google.com,mtklein@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=skia:3255
Review URL: https://codereview.chromium.org/853883004
BUG=skia:3255
I think this supports everything DM used to, but has completely refactored how
it works to fit the design in the bug.
Configs like "tiles-gpu" are automatically wired up.
I wouldn't suggest looking at this as a diff. There's just a bunch of deleted
files, a few new files, and one new file that shares a name with a deleted file
(DM.cpp).
NOTREECHECKS=true
Review URL: https://codereview.chromium.org/788243008
Seems okay after this small patch to skip lockPixels() / unlockPixels().
BUG=skia:3149
CQ_EXTRA_TRYBOTS=client.skia:Test-Ubuntu13.10-GCE-NoGPU-x86_64-Release-TSAN-Trybot
Review URL: https://codereview.chromium.org/773203003
Reason for revert:
Causing breakages on Mac build.
Original issue's description:
> Make nanobench and dm be usable from Chromium build
>
> Move the app logic for each app as follows:
>
> <app>.cpp -- the file which contains main(). Embedders that compile
> their own apps, such as ios shell, upcoming Chromium dm etc, do not use this.
>
> <app>_main.cpp -- the main logic of the Skia test application. This will be
> used by Skia -compiled apps as well as embedder -compiled apps.
>
> <app>_main.h -- the API for the main logic. This will be
> used by Skia -compiled apps as well as embedder -compiled apps.
>
> This way (the upcoming) Chromium dm can setup its Chromium-specific setup
> in custom main(), and then call dm_main(), without the need of any
> SK_BUILD_FOR_XXXX defines controlling whether the tool defines main or not.
>
> BUG=skia:2992
>
> Committed: https://skia.googlesource.com/skia/+/c092d3bdab5f723576cc0346cea3ee282a9cb444TBR=mtklein@chromium.org,mtklein@google.com,borenet@google.com,kkinnunen@nvidia.com
NOTREECHECKS=true
NOTRY=true
BUG=skia:2992
Review URL: https://codereview.chromium.org/724073002
Move the app logic for each app as follows:
<app>.cpp -- the file which contains main(). Embedders that compile
their own apps, such as ios shell, upcoming Chromium dm etc, do not use this.
<app>_main.cpp -- the main logic of the Skia test application. This will be
used by Skia -compiled apps as well as embedder -compiled apps.
<app>_main.h -- the API for the main logic. This will be
used by Skia -compiled apps as well as embedder -compiled apps.
This way (the upcoming) Chromium dm can setup its Chromium-specific setup
in custom main(), and then call dm_main(), without the need of any
SK_BUILD_FOR_XXXX defines controlling whether the tool defines main or not.
BUG=skia:2992
Review URL: https://codereview.chromium.org/657373002
Reason for revert:
Not compiling in ANGLE build
Original issue's description:
> Get gpudft support working in dm, gm, nanobench and bench_pictures
>
> Adds a new config to test distance field text.
> Clean up some flags and #defines to read "distance field text",
> not "distance field fonts" to be consistent with Chromium
>
> NOTREECHECKS=true
>
> Committed: https://skia.googlesource.com/skia/+/06ba179838ba4fe187cf290750aeeb4a02a2960bTBR=bsalomon@google.com,mtklein@google.com,reed@google.com
NOTREECHECKS=true
NOTRY=true
Review URL: https://codereview.chromium.org/707723005
Adds a new config to test distance field text.
Clean up some flags and #defines to read "distance field text",
not "distance field fonts" to be consistent with Chromium
NOTREECHECKS=true
Review URL: https://codereview.chromium.org/699453005
Got to keep our precious data in event of a crash.
With --flushEvery 10 I'm not seeing this cost any wall time.
BUG=skia:
Review URL: https://codereview.chromium.org/653083003
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 makes it considerably cheaper to run SKP recording benchmarks, without
affecting their measurements and without really affecting SKP playback
benchmarks at all.
On my machine, running out/Release/nanobench --match skp --config nondrendering
drops in run time from 6.7s to 2.5s, and the peak RAM usage drops from 129M to 50M.
I'm strongly considering making this lazy decoding the default.
BUG=skia:
R=robertphillips@google.com, mtklein@google.com
Author: mtklein@chromium.org
Review URL: https://codereview.chromium.org/572933006
Today we measure SkPicture playback speed, but not the time it takes to record
the SkPicture. This fixes that by reading SKPs from disk and re-recording them.
On the console, recording shows up first as the nonrendering skp benches,
followed later by the usual playback benches:
maxrss loops min median mean max stddev samples config bench
51M 2 165µs 168µs 169µs 178µs 3% ▆▄▃█▂▄▁▂▁▁ nonrendering tabl_slashdot.skp
57M 1 9.72ms 9.77ms 9.79ms 9.97ms 1% █▂▂▅▃▂▁▄▂▁ nonrendering desk_pokemonwiki.skp
57M 32 2.92µs 2.96µs 3.03µs 3.46µs 6% ▅▁▁▁▁▁▁█▂▁ nonrendering desk_yahoosports.skp
...
147M 1 3.86ms 3.87ms 3.97ms 4.81ms 7% █▁▁▁▁▁▁▁▁▁ 8888 tabl_slashdot.skp_1
147M 1 4.54ms 4.56ms 4.55ms 4.56ms 0% █▅▇▅█▅▂▁▅▁ 565 tabl_slashdot.skp_1
147M 2 3.08ms 3.24ms 4.17ms 8.18ms 50% █▁▁█▁▁▁▁▁▁ gpu tabl_slashdot.skp_1
147M 1 1.61ms 1.62ms 1.69ms 2.33ms 13% █▁▁▁▁▁▁▁▁▁ 8888 desk_pokemonwiki.skp_1
147M 1 1.44ms 1.44ms 1.45ms 1.47ms 1% ▅▂█▂▂▅▁▁▂▁ 565 desk_pokemonwiki.skp_1
...
On skiaperf.com, they'll also be separated out from playback benches by bench_type.
BUG=skia:
R=reed@google.com, mtklein@google.com, jcgregorio@google.com
Author: mtklein@chromium.org
Review URL: https://codereview.chromium.org/559153002
Chrome's using a bounding box, so it's a good idea for our
bots to do so too.
When set, we'll create an SkTileGrid to match the
parameters of --clip, and so should always hit its fast
path.
This will impose a small overhead (querying the BBH) on all
SKPs, but make large SKPs render more quickly. E.g. on
GPU desk_pokemonwiki should show about a 30% improvement,
tabl_mozilla about 40%, and one very long page from my
personal suite, askmefast.com, gets 5x faster.
(The performance changes are not the point of the CL, but
something we should be aware of.)
BUG=
R=bsalomon@google.com, mtklein@google.com, robertphillips@google.com
Author: mtklein@chromium.org
Review URL: https://codereview.chromium.org/497493003
--key describes the type of run (describes the line on the chart), --properties
describes the run itself (describes the dot on the chart).
We'll pass --properties gitHash <git hash> build_number <build number> --key
... to nanobench from the bots.
And... delete a whole lot of dead code.
Example: nanobench --properties gitHash foo build_number 1234 --key bar baz
{
"build_number" : "1234",
"gitHash" : "foo",
"key" : {
"bar" : "baz"
},
"results" : {
....
Friends with https://codereview.chromium.org/491943002
BUG=skia:
R=jcgregorio@google.com, mtklein@google.com
Author: mtklein@chromium.org
Review URL: https://codereview.chromium.org/488213002
Share command flags between dm and unit tests.
Also, allow dm's core to be included by itself and iOSShell.
Command line flags that are the same (or nearly the same) in DM
and in skia_tests have been moved to common_flags. Authors,
please check to see that the shared common flag is correct for
the tool.
For iOS, the 'tool_main' entry point has a wrapper to allow multiple
tools to be statically linked in the iOSShell.
Since SkCommandLineFlags::Parse can only be called once, these calls
are disabled in the IOS build.
Since the iOS app directory is dynamically assigned a name, use '@' to
select it. (This is the same convention chosen by the Mobile Harness
iOS file system utilities.)
Move the heart of dm.gyp into dm.gypi so that it can be included by
itself and iOSShell.gyp.
Add tools/flags/SkCommonFlags.* to define and declare common
command line flags.
Add support for dm to iOSShell.
BUG=skia:
R=scroggo@google.com, mtklein@google.com, jvanverth@google.com, bsalomon@google.com
Author: caryclark@google.com
Review URL: https://codereview.chromium.org/389653004
We're moving away from BigQuery for storing results so the output doens't have to conform to BQ requirements, which allows simplifying the format. Also stop parsing the filename for information and pass in buildbot parameters explicitly.
Adds the following flags to nanobench:
--key
--gitHash
BUG=skia:
R=mtklein@google.com, bsalomon@google.com
Author: jcgregorio@google.com
Review URL: https://codereview.chromium.org/392393002
This seems to be ~100x higher resolution than QueryPerformanceCounter. AFAIK, all our Windows perf bots have constant_tsc, so we can be a bit more direct about using rdtsc directly: it'll always tick at the max CPU frequency.
Now, the question remains, what is the max CPU frequency to divide through by? It looks like QueryPerformanceFrequency actually gives the CPU frequency in kHz, suspiciously exactly what we need to divide through to get elapsed milliseconds. That was a freebie.
I did some before/after comparison on slow benchmarks. Timings look the same. Going to land this without review tonight to see what happens on the bots; happy to review carefully tomorrow.
R=mtklein@google.com
TBR=bungeman
BUG=skia:
Review URL: https://codereview.chromium.org/394363003
