Reason for revert:
Speculative to fix windows bots
Original issue's description:
> Treat bad values passed to --images as a fatal error
>
> If an option is passed to --images that is either a non-existent path or
> a folder with no images matching the supported types, assume this is
> an error and exit, so they can supply a valid path instead.
>
> Share code between DM and nanobench in SkCommonFlags.
>
> nanobench now behaves more like DM - it will check a directory for
> images that match the supported extensions.
>
> Only consider image paths ending in RAW suffixes as images if
> SK_CODE_DECODES_RAW is defined. This prevents us from seeing failure
> to decode errors on platforms that cannot decode it.
>
> GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1611323004
>
> Committed: https://skia.googlesource.com/skia/+/7579786f3bd5a8fda84a1abc45b16213c3371f93TBR=mtklein@google.com,borenet@google.com,msarett@google.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
# Not skipping CQ checks because original CL landed more than 1 days ago.
Review URL: https://codereview.chromium.org/1653543002
If an option is passed to --images that is either a non-existent path or
a folder with no images matching the supported types, assume this is
an error and exit, so they can supply a valid path instead.
Share code between DM and nanobench in SkCommonFlags.
nanobench now behaves more like DM - it will check a directory for
images that match the supported extensions.
Only consider image paths ending in RAW suffixes as images if
SK_CODE_DECODES_RAW is defined. This prevents us from seeing failure
to decode errors on platforms that cannot decode it.
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1611323004
Review URL: https://codereview.chromium.org/1611323004
Local timing says this 4-byte Paeth function takes about 0.3x the time the serial libpng code does, dropping from ~10 cycles per byte to ~2.9.
bpp=4 is mainly an easy demo. This approach can work for any bpp up to 16, 1 pixel at a time, at roughly the same cost per pixel. Doing more than 1 pixel at a time is a tricky math problem I have yet to attempt to solve.
Everything here can be trivially downgraded to MMX, supporting bpp up to 8. It seems to be a little slower (~3.5 cycles per byte), but it would make the code compatible with every x86 that can still power on.
I've tried four approaches:
- this way;
- doing things naively in 16-bit;
- a 16-bit version that requires division by 3 (i.e. mulhi_epu16(..., 0x5580) );
- a mostly 8-bit version of the same.
They're all fine, but this one is consistently the fastest I've measured.
I'd be happy to settle on the naive 16-bit version too, which would have a very clear implementation that's only minorly slower than this version. The other two are way more complicated, and would require us to draw some serious ASCII diagrams to explain.
I have learned that the .skp serialization tests (serialize-8888) have a nice side effect of testing the correctness of these filters!
(Since writing the description above, I've bumped things up to {Paeth,Sub,Avg} x { 3 bpp, 4 bpp }.)
BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1573943002
Review URL: https://codereview.chromium.org/1573943002
Reason for revert:
Bot failures
Original issue's description:
> AVX 2 SrcOver blits: color32, blitmask.
>
> As a follow up to the SSE 4.1 CL, this should look pretty familiar.
>
> I've made some organizational changes around how we load, store, pack, and unpack data that I think makes things clearer and more orthogonal, and it'll make it easier to try out a pmaddubsw lerp. I have backported these changes to the SSE 4.1 code, and I hope that I can actually get a lot of this code templated for sharing between the two later.
>
> Perf changes (relative to SSE 4.1):
> Xfermode_SrcOver: 1650 -> 1180 (0.71x) // large opaque blit
> Xfermode_SrcOver_aa: 1794 -> 1653 (0.92x) // large opaque + small transparent
> text_16_AA_{FF,BK,WT}: 1.72 -> 1.59 (0.92x) // small opaque blit
> text_16_AA_88: 1.83 -> 1.77 (0.97x) // small transparent blit
>
> This should be a big throughout win, and a small latency win.
> This should all be pixel-exact to the previous SSE 4.1 code.
>
>
> GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1532613002
> CQ_EXTRA_TRYBOTS=client.skia:Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release-SKNX_NO_SIMD-Trybot;client.skia.compile:Build-Ubuntu-GCC-x86_64-Release-CMake-Trybot,Build-Mac10.9-Clang-x86_64-Release-CMake-Trybot
>
> Committed: https://skia.googlesource.com/skia/+/5d2117015eb271e09faf4a7ddd89093c9d618a36TBR=herb@google.com,mtklein@google.com,mtklein@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
Review URL: https://codereview.chromium.org/1632713002
As a follow up to the SSE 4.1 CL, this should look pretty familiar.
I've made some organizational changes around how we load, store, pack, and unpack data that I think makes things clearer and more orthogonal, and it'll make it easier to try out a pmaddubsw lerp. I have backported these changes to the SSE 4.1 code, and I hope that I can actually get a lot of this code templated for sharing between the two later.
Perf changes (relative to SSE 4.1):
Xfermode_SrcOver: 1650 -> 1180 (0.71x) // large opaque blit
Xfermode_SrcOver_aa: 1794 -> 1653 (0.92x) // large opaque + small transparent
text_16_AA_{FF,BK,WT}: 1.72 -> 1.59 (0.92x) // small opaque blit
text_16_AA_88: 1.83 -> 1.77 (0.97x) // small transparent blit
This should be a big throughout win, and a small latency win.
This should all be pixel-exact to the previous SSE 4.1 code.
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1532613002
CQ_EXTRA_TRYBOTS=client.skia:Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release-SKNX_NO_SIMD-Trybot;client.skia.compile:Build-Ubuntu-GCC-x86_64-Release-CMake-Trybot,Build-Mac10.9-Clang-x86_64-Release-CMake-Trybot
Review URL: https://codereview.chromium.org/1532613002
Try to start faster:
- remove flags dependency
- print nothing
- strip unused symbols from the binary on Mac (smaller binary)
- only create one fuzz object
- only run one DEF_FUZZ
I am not sure if any of these things mattered, but I thought you may like to look.
Good stuff:
- make nextU() / nextF() work
- drop nextURange() / nextFRange() for now
- add nextB() for a single byte
As you may have guessed, I have figured out how to use afl-fuzz on my laptop.
Syntax to run becomes:
$ afl-fuzz ... out/Release/fuzz <DEF_FUZZ name> @@
BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1581203003
Review URL: https://codereview.chromium.org/1581203003
Simplify path id allocation in NVPR backend. Instead of using
an AVL tree of path id ranges for the first 65535 ids, use just
a simple stategy of overallocation and "bump index".
Fixes the bug where previously overallocated ids were not deleted.
The advantage is that the implementation is simple and all allocations
go through overallocation, not just the first 65535 of the 1-range
allocations.
Removes the logic where paths were cleared with setting path data to
null instead of deleting the whole path. Now deleted paths are just
deleted normally. These operations should have equivalent performance on
command buffer. Deleting the path should enable the driver to do more
maintainance.
Removes the GLNameAllocator, as it was only used for paths. In order for
it to be used for other IDs, it probably would need to be re-written to
support cleanup and arbitrary ranges. Also, the interface would probably
need to be changed to not requiring the block to be allocated before it
could be managed by the structure.
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1150243003
Review URL: https://codereview.chromium.org/1150243003
Remove refcounting from SkGLContext.
SkGLContext is expected to behave like GrContextFactory would own
it, as implied by the GrContextFactory function.
If it is refcounted, this does not hold.
Also other use sites, such as in SkOSWindow_win (command buffer gl
object), confirm the behavior. The object is explicitly owned and
destroyed, not shared.
Also fixes potential crashes from using GL context of an abandoned
context.
Also fixes potential crashes in DM/nanobench, if the GrContext lives
longer than GLContext through internal refing of GrContext.
Moves the non-trivial implementations from GrContextFactory.h to
.cpp, just for consistency sake.
Changes pathops_unittest.gyp. The pathops_unittest uses
GrContextFactory, but did not link to its implementation. The reason
they worked was that the implementation used (constructors, destructors)
happened to be in the .h file.
This works towards being able to use command buffer and NVPR from
the SampleApp.
BUG=skia:2992
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1511773005
Committed: https://skia.googlesource.com/skia/+/830e012187f951d49d7e46e196ac8d1e653a25da
Review URL: https://codereview.chromium.org/1511773005
SkUtility.h and SkTLogic.h implement a number of type traits now
available through <type_traits> and <utility>. This removes SkUtility.h,
replacing it with <utility>, and moves a number of traits in
SkTLogic.h to use the std:: equivelents. This change only uses C++11
parts of the standard library; SkTLogic.h will continue to provide
C++14 and beyond for now in the skstd namespace.
The changes to SkTLogic.h are being done gradually so that safe changes
may be landed confidently, with more risky changes in the future.
Review URL: https://codereview.chromium.org/1561683002
Reason for revert:
Broke tests on Android, iOS, Mac and Windows.
Original issue's description:
> Make SkGLContext lifetime more well-defined
>
> Remove refcounting from SkGLContext.
>
> SkGLContext is expected to behave like GrContextFactory would own
> it, as implied by the GrContextFactory function.
>
> If it is refcounted, this does not hold.
>
> Also other use sites, such as in SkOSWindow_win (command buffer gl
> object), confirm the behavior. The object is explicitly owned and
> destroyed, not shared.
>
> Also fixes potential crashes from using GL context of an abandoned
> context.
>
> Also fixes potential crashes in DM/nanobench, if the GrContext lives
> longer than GLContext through internal refing of GrContext.
>
> Moves the non-trivial implementations from GrContextFactory.h to
> .cpp, just for consistency sake.
>
> Changes pathops_unittest.gyp. The pathops_unittest uses
> GrContextFactory, but did not link to its implementation. The reason
> they worked was that the implementation used (constructors, destructors)
> happened to be in the .h file.
>
> This works towards being able to use command buffer and NVPR from
> the SampleApp.
>
> BUG=skia:2992
> GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1511773005
>
> Committed: https://skia.googlesource.com/skia/+/830e012187f951d49d7e46e196ac8d1e653a25daTBR=bsalomon@google.com,kkinnunen@nvidia.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:2992
Review URL: https://codereview.chromium.org/1555053003
Remove refcounting from SkGLContext.
SkGLContext is expected to behave like GrContextFactory would own
it, as implied by the GrContextFactory function.
If it is refcounted, this does not hold.
Also other use sites, such as in SkOSWindow_win (command buffer gl
object), confirm the behavior. The object is explicitly owned and
destroyed, not shared.
Also fixes potential crashes from using GL context of an abandoned
context.
Also fixes potential crashes in DM/nanobench, if the GrContext lives
longer than GLContext through internal refing of GrContext.
Moves the non-trivial implementations from GrContextFactory.h to
.cpp, just for consistency sake.
Changes pathops_unittest.gyp. The pathops_unittest uses
GrContextFactory, but did not link to its implementation. The reason
they worked was that the implementation used (constructors, destructors)
happened to be in the .h file.
This works towards being able to use command buffer and NVPR from
the SampleApp.
BUG=skia:2992
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1511773005
Review URL: https://codereview.chromium.org/1511773005
Add extended config specification form that can be used to run different
gpu backend with different APIs.
The configs can be specified with the form:
gpu(api=string,dit=bool,nvpr=bool,samples=int)
This replaces and removes the --gpuAPI flag.
All existing configs should still work.
Adds following documentation:
out/Debug/dm --help config
Flags:
--config: type: string default: 565 8888 gpu nonrendering
Options: 565 8888 debug gpu gpudebug gpudft gpunull msaa16 msaa4
nonrendering null nullgpu nvprmsaa16 nvprmsaa4 pdf pdf_poppler skp svg
xps or use extended form 'backend(option=value,...)'.
Extended form: 'backend(option=value,...)'
Possible backends and options:
gpu(api=string,dit=bool,nvpr=bool,samples=int) GPU backend
api type: string default: native.
Select graphics API to use with gpu backend.
Options:
native Use platform default OpenGL or OpenGL ES backend.
gl Use OpenGL.
gles Use OpenGL ES.
debug Use debug OpenGL.
null Use null OpenGL.
dit type: bool default: false.
Use device independent text.
nvpr type: bool default: false.
Use NV_path_rendering OpenGL and OpenGL ES extension.
samples type: int default: 0.
Use multisampling with N samples.
Predefined configs:
gpu = gpu()
msaa4 = gpu(samples=4)
msaa16 = gpu(samples=16)
nvprmsaa4 = gpu(nvpr=true,samples=4)
nvprmsaa16 = gpu(nvpr=true,samples=16)
gpudft = gpu(dit=true)
gpudebug = gpu(api=debug)
gpunull = gpu(api=null)
debug = gpu(api=debug)
nullgpu = gpu(api=null)
BUG=skia:2992
Committed: https://skia.googlesource.com/skia/+/e13ca329fca4c28cf4e078561f591ab27b743d23
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1490113005
Committed: https://skia.googlesource.com/skia/+/c8b4336444e7b90382e04e33665fb3b8490b825b
Committed: https://skia.googlesource.com/skia/+/9ebc3f0ee6db215dde461dc4777d85988cf272dd
Review URL: https://codereview.chromium.org/1490113005
Add extended config specification form that can be used to run different
gpu backend with different APIs.
The configs can be specified with the form:
gpu(api=string,dit=bool,nvpr=bool,samples=int)
This replaces and removes the --gpuAPI flag.
All existing configs should still work.
Adds following documentation:
out/Debug/dm --help config
Flags:
--config: type: string default: 565 8888 gpu nonrendering
Options: 565 8888 debug gpu gpudebug gpudft gpunull msaa16 msaa4
nonrendering null nullgpu nvprmsaa16 nvprmsaa4 pdf pdf_poppler skp svg
xps or use extended form 'backend(option=value,...)'.
Extended form: 'backend(option=value,...)'
Possible backends and options:
gpu(api=string,dit=bool,nvpr=bool,samples=int) GPU backend
api type: string default: native.
Select graphics API to use with gpu backend.
Options:
native Use platform default OpenGL or OpenGL ES backend.
gl Use OpenGL.
gles Use OpenGL ES.
debug Use debug OpenGL.
null Use null OpenGL.
dit type: bool default: false.
Use device independent text.
nvpr type: bool default: false.
Use NV_path_rendering OpenGL and OpenGL ES extension.
samples type: int default: 0.
Use multisampling with N samples.
Predefined configs:
gpu = gpu()
msaa4 = gpu(samples=4)
msaa16 = gpu(samples=16)
nvprmsaa4 = gpu(nvpr=true,samples=4)
nvprmsaa16 = gpu(nvpr=true,samples=16)
gpudft = gpu(dit=true)
gpudebug = gpu(api=debug)
gpunull = gpu(api=null)
debug = gpu(api=debug)
nullgpu = gpu(api=null)
BUG=skia:2992
Committed: https://skia.googlesource.com/skia/+/e13ca329fca4c28cf4e078561f591ab27b743d23
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1490113005
Committed: https://skia.googlesource.com/skia/+/c8b4336444e7b90382e04e33665fb3b8490b825b
Review URL: https://codereview.chromium.org/1490113005
Reason for revert:
This CL changed 1200 images on gold, when I wouldn't expect any diffs from the description.
Original issue's description:
> Add config options to run different GPU APIs to dm and nanobench
>
> Add extended config specification form that can be used to run different
> gpu backend with different APIs.
>
> The configs can be specified with the form:
> gpu(api=string,dit=bool,nvpr=bool,samples=int)
>
> This replaces and removes the --gpuAPI flag.
>
> All existing configs should still work.
>
> Adds following documentation:
>
> out/Debug/dm --help config
>
> Flags:
> --config: type: string default: 565 8888 gpu nonrendering
> Options: 565 8888 debug gpu gpudebug gpudft gpunull msaa16 msaa4
> nonrendering null nullgpu nvprmsaa16 nvprmsaa4 pdf pdf_poppler skp svg
> xps or use extended form 'backend(option=value,...)'.
>
> Extended form: 'backend(option=value,...)'
>
> Possible backends and options:
>
> gpu(api=string,dit=bool,nvpr=bool,samples=int) GPU backend
> api type: string default: native.
> Select graphics API to use with gpu backend.
> Options:
> native Use platform default OpenGL or OpenGL ES backend.
> gl Use OpenGL.
> gles Use OpenGL ES.
> debug Use debug OpenGL.
> null Use null OpenGL.
> dit type: bool default: false.
> Use device independent text.
> nvpr type: bool default: false.
> Use NV_path_rendering OpenGL and OpenGL ES extension.
> samples type: int default: 0.
> Use multisampling with N samples.
>
> Predefined configs:
>
> gpu = gpu()
> msaa4 = gpu(samples=4)
> msaa16 = gpu(samples=16)
> nvprmsaa4 = gpu(nvpr=true,samples=4)
> nvprmsaa16 = gpu(nvpr=true,samples=16)
> gpudft = gpu(dit=true)
> gpudebug = gpu(api=debug)
> gpunull = gpu(api=null)
> debug = gpu(api=debug)
> nullgpu = gpu(api=null)
>
> BUG=skia:2992
>
> Committed: https://skia.googlesource.com/skia/+/e13ca329fca4c28cf4e078561f591ab27b743d23
> GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1490113005
>
> Committed: https://skia.googlesource.com/skia/+/c8b4336444e7b90382e04e33665fb3b8490b825bTBR=mtklein@google.com,bsalomon@google.com,scroggo@google.com,kkinnunen@nvidia.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:2992
Review URL: https://codereview.chromium.org/1536963002
Add extended config specification form that can be used to run different
gpu backend with different APIs.
The configs can be specified with the form:
gpu(api=string,dit=bool,nvpr=bool,samples=int)
This replaces and removes the --gpuAPI flag.
All existing configs should still work.
Adds following documentation:
out/Debug/dm --help config
Flags:
--config: type: string default: 565 8888 gpu nonrendering
Options: 565 8888 debug gpu gpudebug gpudft gpunull msaa16 msaa4
nonrendering null nullgpu nvprmsaa16 nvprmsaa4 pdf pdf_poppler skp svg
xps or use extended form 'backend(option=value,...)'.
Extended form: 'backend(option=value,...)'
Possible backends and options:
gpu(api=string,dit=bool,nvpr=bool,samples=int) GPU backend
api type: string default: native.
Select graphics API to use with gpu backend.
Options:
native Use platform default OpenGL or OpenGL ES backend.
gl Use OpenGL.
gles Use OpenGL ES.
debug Use debug OpenGL.
null Use null OpenGL.
dit type: bool default: false.
Use device independent text.
nvpr type: bool default: false.
Use NV_path_rendering OpenGL and OpenGL ES extension.
samples type: int default: 0.
Use multisampling with N samples.
Predefined configs:
gpu = gpu()
msaa4 = gpu(samples=4)
msaa16 = gpu(samples=16)
nvprmsaa4 = gpu(nvpr=true,samples=4)
nvprmsaa16 = gpu(nvpr=true,samples=16)
gpudft = gpu(dit=true)
gpudebug = gpu(api=debug)
gpunull = gpu(api=null)
debug = gpu(api=debug)
nullgpu = gpu(api=null)
BUG=skia:2992
Committed: https://skia.googlesource.com/skia/+/e13ca329fca4c28cf4e078561f591ab27b743d23
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1490113005
Review URL: https://codereview.chromium.org/1490113005
Reason for revert:
speculative revert to see if it unblocks the DEPS roll
https://codereview.chromium.org/1529443002
Original issue's description:
> Add config options to run different GPU APIs to dm and nanobench
>
> Add extended config specification form that can be used to run different
> gpu backend with different APIs.
>
> The configs can be specified with the form:
> gpu(api=string,dit=bool,nvpr=bool,samples=int)
>
> This replaces and removes the --gpuAPI flag.
>
> All existing configs should still work.
>
> Adds following documentation:
>
> out/Debug/dm --help config
>
> Flags:
> --config: type: string default: 565 8888 gpu nonrendering
> Options: 565 8888 debug gpu gpudebug gpudft gpunull msaa16 msaa4
> nonrendering null nullgpu nvprmsaa16 nvprmsaa4 pdf pdf_poppler skp svg
> xps or use extended form 'backend(option=value,...)'.
>
> Extended form: 'backend(option=value,...)'
>
> Possible backends and options:
>
> gpu(api=string,dit=bool,nvpr=bool,samples=int) GPU backend
> api type: string default: native.
> Select graphics API to use with gpu backend.
> Options:
> native Use platform default OpenGL or OpenGL ES backend.
> gl Use OpenGL.
> gles Use OpenGL ES.
> debug Use debug OpenGL.
> null Use null OpenGL.
> dit type: bool default: false.
> Use device independent text.
> nvpr type: bool default: false.
> Use NV_path_rendering OpenGL and OpenGL ES extension.
> samples type: int default: 0.
> Use multisampling with N samples.
>
> Predefined configs:
>
> gpu = gpu()
> msaa4 = gpu(samples=4)
> msaa16 = gpu(samples=16)
> nvprmsaa4 = gpu(nvpr=true,samples=4)
> nvprmsaa16 = gpu(nvpr=true,samples=16)
> gpudft = gpu(dit=true)
> gpudebug = gpu(api=debug)
> gpunull = gpu(api=null)
> debug = gpu(api=debug)
> nullgpu = gpu(api=null)
>
> BUG=skia:2992
>
> Committed: https://skia.googlesource.com/skia/+/e13ca329fca4c28cf4e078561f591ab27b743d23TBR=bsalomon@google.com,scroggo@google.com,joshualitt@google.com,kkinnunen@nvidia.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:2992
Review URL: https://codereview.chromium.org/1528473002
Add extended config specification form that can be used to run different
gpu backend with different APIs.
The configs can be specified with the form:
gpu(api=string,dit=bool,nvpr=bool,samples=int)
This replaces and removes the --gpuAPI flag.
All existing configs should still work.
Adds following documentation:
out/Debug/dm --help config
Flags:
--config: type: string default: 565 8888 gpu nonrendering
Options: 565 8888 debug gpu gpudebug gpudft gpunull msaa16 msaa4
nonrendering null nullgpu nvprmsaa16 nvprmsaa4 pdf pdf_poppler skp svg
xps or use extended form 'backend(option=value,...)'.
Extended form: 'backend(option=value,...)'
Possible backends and options:
gpu(api=string,dit=bool,nvpr=bool,samples=int) GPU backend
api type: string default: native.
Select graphics API to use with gpu backend.
Options:
native Use platform default OpenGL or OpenGL ES backend.
gl Use OpenGL.
gles Use OpenGL ES.
debug Use debug OpenGL.
null Use null OpenGL.
dit type: bool default: false.
Use device independent text.
nvpr type: bool default: false.
Use NV_path_rendering OpenGL and OpenGL ES extension.
samples type: int default: 0.
Use multisampling with N samples.
Predefined configs:
gpu = gpu()
msaa4 = gpu(samples=4)
msaa16 = gpu(samples=16)
nvprmsaa4 = gpu(nvpr=true,samples=4)
nvprmsaa16 = gpu(nvpr=true,samples=16)
gpudft = gpu(dit=true)
gpudebug = gpu(api=debug)
gpunull = gpu(api=null)
debug = gpu(api=debug)
nullgpu = gpu(api=null)
BUG=skia:2992
Review URL: https://codereview.chromium.org/1490113005
