[chromium] API to pass impl thread via WebLayerTreeView
https://bugs.webkit.org/show_bug.cgi?id=99863

Reviewed by James Robinson.

This adds an API to pass the compositor impl thread via WebView and
WebLayerTreeView. This is currently a no-op change, but in the future
this codepath will supercede WebCompositor. The goal is to avoid statics
in compositor initialization.

Source/Platform:

* chromium/public/WebCompositorSupport.h:
(WebKit::WebCompositorSupport::createLayerTreeView):
(WebCompositorSupport):
* chromium/public/WebLayerTreeView.h:
(WebKit):
(WebLayerTreeView):

Source/WebKit/chromium:

* public/WebView.h:
(WebKit):
(WebView):
* src/WebViewImpl.cpp:
(WebKit::WebViewImpl::WebViewImpl):
(WebKit::WebViewImpl::setCompositorImplThread):
(WebKit):
(WebKit::WebViewImpl::setIsAcceleratedCompositingActive):
* src/WebViewImpl.h:
(WebViewImpl):
* tests/GraphicsLayerChromiumTest.cpp:
(WebKit::GraphicsLayerChromiumTest::GraphicsLayerChromiumTest):

Tools:

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


git-svn-id: https://svn.webkit.org/repository/webkit/trunk/Source/Platform/chromium/public@131944 268f45cc-cd09-0410-ab3c-d52691b4dbfc