[chromium] Move check for threaded compositing from WebCompositorSupport to Platform
https://bugs.webkit.org/show_bug.cgi?id=111386

Reviewed by Adrienne Walker.

Source/Platform:

This moves the query for if threaded compositing is enabled from WebCompositorSupport
to Platform. This is part of an effort to remove statefulness on WebCompositorSupport
and because it's much easier to override Platform functions for different tests.

* chromium/public/Platform.h:
(WebKit::Platform::isThreadedCompositingEnabled):
(Platform):
* chromium/public/WebCompositorSupport.h:

Source/WebCore:

This moves checks for whether threaded compositing is enabled from WebCompositorSupport
to Platform. In the case of Canvas2DLayerBridge, the check is moved completely out of
the class to make it easier for tests to specify the threaded configuration to use in the test.

* platform/graphics/chromium/Canvas2DLayerBridge.cpp:
(WebCore::Canvas2DLayerBridge::Canvas2DLayerBridge):
* platform/graphics/chromium/Canvas2DLayerBridge.h:
(WebCore::Canvas2DLayerBridge::create):
(Canvas2DLayerBridge):
* platform/graphics/chromium/DrawingBufferChromium.cpp:
(WebCore::DrawingBuffer::DrawingBuffer):
* platform/graphics/skia/ImageBufferSkia.cpp:
(WebCore::createAcceleratedCanvas):

Source/WebKit/chromium:

* src/WebViewImpl.cpp:
(WebKit::WebViewImpl::composite):
(WebKit::WebViewImpl::scheduleAnimation):
(WebKit::WebViewImpl::setIsAcceleratedCompositingActive):
(WebKit::WebViewImpl::scheduleComposite):
* tests/Canvas2DLayerBridgeTest.cpp:
(Canvas2DLayerBridgeTest::fullLifecycleTest):
* tests/Canvas2DLayerManagerTest.cpp:
(FakeCanvas2DLayerBridge::FakeCanvas2DLayerBridge):

Tools:

* DumpRenderTree/chromium/TestShell.cpp:
(TestShell::initialize):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@144827 268f45cc-cd09-0410-ab3c-d52691b4dbfc