https://bugs.webkit.org/show_bug.cgi?id=66820

Reviewed by Kenneth Russell.

Source/WebCore:

Adds support for recreating a context as if it was lost, and fixes
compositeAndReadback() to attempt context recovery.

Test: platform/chromium/compositing/lost-compositor-context.html

* platform/graphics/chromium/cc/CCLayerTreeHost.cpp:
(WebCore::CCLayerTreeHost::compositeAndReadback):
(WebCore::CCLayerTreeHost::loseCompositorContext):
* platform/graphics/chromium/cc/CCLayerTreeHost.h:

Source/WebKit/chromium:

Adds a testing-only API to simulate a lost compositor context.

* public/WebView.h:
* src/WebViewImpl.cpp:
(WebKit::WebViewImpl::loseCompositorContext):
* src/WebViewImpl.h:

Tools:

Exposes a LayoutTestController interface in chromium to simulate a
lost compositor context.

* DumpRenderTree/chromium/LayoutTestController.cpp:
(LayoutTestController::LayoutTestController):
(LayoutTestController::loseCompositorContext):
* DumpRenderTree/chromium/LayoutTestController.h:

LayoutTests:

Adds a simple test for losing the compositor context in a recoverable
way on a composited page. Tests that we recover without crashing and
render the updated content on the next frame.

* platform/chromium/compositing/lost-compositor-context.html: Added.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@93681 268f45cc-cd09-0410-ab3c-d52691b4dbfc