Fix lost context race with fullscreen pepper widget.

An ill-timed lost context could destroy the compositor context, while a
composite has been scheduled. This makes sure we reset
is_accelerated_compositing_active_ so that we don't try to use the 3D path in
this case.

BUG=None
TEST=Fullscreen with Pepper Flash on ARM devices


Review URL: http://codereview.chromium.org/7628023

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@96677 0039d316-1c4b-4281-b951-d872f2087c98

content/renderer/render_widget_fullscreen_pepper.cc

@@ -462,10 +462,10 @@ bool RenderWidgetFullscreenPepper::InitContext() {
 }
 
 bool RenderWidgetFullscreenPepper::CheckCompositing() {
-  bool compositing = webwidget_->isAcceleratedCompositingActive();
-  if (compositing != is_accelerated_compositing_active_) {
+  bool compositing =
+      webwidget_ && webwidget_->isAcceleratedCompositingActive();
+  if (compositing != is_accelerated_compositing_active_)
     didActivateAcceleratedCompositing(compositing);
-  }
   return compositing;
 }
 
@@ -489,6 +489,7 @@ void RenderWidgetFullscreenPepper::OnLostContext(
   program_ = 0;
   buffer_ = 0;
   OnSwapBuffersAborted();
+  CheckCompositing();
 }
 
 void RenderWidgetFullscreenPepper::OnSwapBuffersCompleteByRendererGLContext() {