Remove obsolete references to threaded-compositing and impl-side-painting flags.

content/test/gpu/gpu_tests/gpu_rasterization.py

Index: content/test/gpu/gpu_tests/gpu_rasterization.py
diff --git a/content/test/gpu/gpu_tests/gpu_rasterization.py b/content/test/gpu/gpu_tests/gpu_rasterization.py
index f313d8b56a47766c1fa040a5c7944177ef87099d..a2a10debd93ef3914d7ff2cc533eb8b8c245fd9b 100644
--- a/content/test/gpu/gpu_tests/gpu_rasterization.py
+++ b/content/test/gpu/gpu_tests/gpu_rasterization.py
@@ -35,7 +35,6 @@ class GpuRasterizationValidator(cloud_storage_test_base.ValidatorBase):
     # --test-type=gpu is used only to suppress the "Google API Keys are missing"
     # infobar, which causes flakiness in tests.
     options.AppendExtraBrowserArgs(['--enable-threaded-compositing',

[danakj, 2016/09/26 21:39:29]

I think this should go away too

[wkorman, 2016/09/26 21:44:29]

Are you sure? It looks like this still ties to some actual logic, as
!kEnableThreadedCompositing -> kDisableThreadedAnimation ->
is_threaded_animation_enabled:

https://cs.chromium.org/chromium/src/content/renderer/render_thread_impl.cc?c...

[danakj, 2016/09/26 21:46:06]

In layout tests we disable threaded compositing unless the flag is present. It
has no meaning outside of layout tests.

[Ken Russell (switch to Gerrit), 2016/09/26 21:48:57]

+1 for removing it then. Thanks danakj@ for pointing this out. These command
line flags were chosen a long time ago, before the compositor's current
behavior.

[wkorman, 2016/09/26 22:18:54]

Done.

-                                    '--enable-impl-side-painting',
                                     '--force-gpu-rasterization',
                                     '--enable-gpu-benchmarking',
                                     '--test-type=gpu'])