Add shared bitmap managers for browser and renderer processes.

cc/output/delegating_renderer.cc

Index: cc/output/delegating_renderer.cc
diff --git a/cc/output/delegating_renderer.cc b/cc/output/delegating_renderer.cc
index e56d1465a1683728d6b607d68f6ca6c961754df5..30caa7a0e046507d782524f85480cb3a556ba7fc 100644
--- a/cc/output/delegating_renderer.cc
+++ b/cc/output/delegating_renderer.cc
@@ -161,8 +161,8 @@ void DelegatingRenderer::SetVisible(bool visible) {
   // We loop visibility to the GPU process, since that's what manages memory.
   // That will allow it to feed us with memory allocations that we can act
   // upon.
-  DCHECK(context_provider);
-  context_provider->ContextSupport()->SetSurfaceVisible(visible);
+  if (context_provider)
+    context_provider->ContextSupport()->SetSurfaceVisible(visible);
 }
 
 void DelegatingRenderer::SendManagedMemoryStats(size_t bytes_visible,