Fixes leak/crash in CompositorCC.

BUG=104360
TEST=covered by tests


Review URL: http://codereview.chromium.org/8772047

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@112843 0039d316-1c4b-4281-b951-d872f2087c98

ui/gfx/compositor/compositor_cc.cc

@@ -145,6 +145,10 @@ CompositorCC::CompositorCC(CompositorDelegate* delegate,
 }
 
 CompositorCC::~CompositorCC() {
+  // There's a cycle between |root_web_layer_| and |host_|, which results in
+  // leaking and/or crashing. Explicitly set the root layer to NULL so the cycle
+  // is broken.
+  host_.setRootLayer(NULL);
 }
 
 void CompositorCC::Initialize(bool use_thread) {