[chromium] Use WebCompositor interface in Platform API instead of CCProxy to query threaded compositor status
https://bugs.webkit.org/show_bug.cgi?id=93398

Reviewed by Adam Barth.

Source/Platform:

Adds thread status query interfaces to WebCompositor for WebKit code that wants to know if we are in threaded
mode.

* chromium/public/WebCompositor.h:
(WebCompositor):

Source/WebCore:

Converts non-compositor code that cares about threaded compositing status over to query WebCompositor instead of
CCProxy.

* page/scrolling/chromium/ScrollingCoordinatorChromium.cpp:
* platform/chromium/support/WebCompositorImpl.cpp:
(WebKit):
(WebKit::WebCompositor::threadingEnabled):
(WebKit::WebCompositor::onCompositorThread):
(WebKit::WebCompositorImpl::threadingEnabled):
* platform/chromium/support/WebCompositorImpl.h:
(WebCompositorImpl):
* platform/graphics/chromium/Canvas2DLayerBridge.cpp:
(WebCore::Canvas2DLayerBridge::Canvas2DLayerBridge):
* platform/graphics/chromium/DrawingBufferChromium.cpp:
(WebCore::DrawingBuffer::DrawingBuffer):

Source/WebKit/chromium:

Converts non-compositor code that cares about threaded compositing status over to query WebCompositor instead of
CCProxy.

* src/WebMediaPlayerClientImpl.cpp:
(WebKit::WebMediaPlayerClientImpl::supportsType):
* src/WebViewImpl.cpp:
(WebKit::WebViewImpl::composite):
(WebKit::WebViewImpl::scheduleAnimation):
(WebKit::WebViewImpl::scheduleComposite):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@124925 268f45cc-cd09-0410-ab3c-d52691b4dbfc