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 bca2a42bc248f04c1b9104b5ebe3f39abd852bbb..06f6a9ad3628bd6dbc8f5c5343dd20a314bfb5cc 100644
--- a/cc/output/delegating_renderer.cc
+++ b/cc/output/delegating_renderer.cc
@@ -163,8 +163,8 @@ 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,