3D Compositing in <browser>, first draft.

content/browser/gpu/gpu_process_host.cc

Index: content/browser/gpu/gpu_process_host.cc
diff --git a/content/browser/gpu/gpu_process_host.cc b/content/browser/gpu/gpu_process_host.cc
index 7a13cbf3d6e7274f0aa81c4c2d65bbf64fe10daa..aa399f8ce03adb33060b0a17e57f869299558a0a 100644
--- a/content/browser/gpu/gpu_process_host.cc
+++ b/content/browser/gpu/gpu_process_host.cc
@@ -521,16 +521,18 @@ void GpuProcessHost::CreateViewCommandBuffer(
   DCHECK(CalledOnValidThread());
 
 #if defined(TOOLKIT_GTK)
-  // There should only be one such command buffer (for the compositor).  In
-  // practice, if the GPU process lost a context, GraphicsContext3D with
-  // associated command buffer and view surface will not be gone until new
-  // one is in place and all layers are reattached.
   linked_ptr<SurfaceRef> surface_ref;
-  SurfaceRefMap::iterator it = surface_refs_.find(surface_id);
-  if (it != surface_refs_.end())
-    surface_ref = (*it).second;
-  else
-    surface_ref.reset(new SurfaceRef(compositing_surface.handle));
+  if (compositing_surface.handle) {
+    // There should only be one such command buffer (for the compositor).  In
+    // practice, if the GPU process lost a context, GraphicsContext3D with
+    // associated command buffer and view surface will not be gone until new
+    // one is in place and all layers are reattached.
+    SurfaceRefMap::iterator it = surface_refs_.find(surface_id);
+    if (it != surface_refs_.end())
+      surface_ref = (*it).second;
+    else
+      surface_ref.reset(new SurfaceRef(compositing_surface.handle));
+  }
 #endif  // defined(TOOLKIT_GTK)
 
   if (!compositing_surface.is_null() &&
@@ -538,7 +540,8 @@ void GpuProcessHost::CreateViewCommandBuffer(
           compositing_surface, surface_id, client_id, init_params))) {
     create_command_buffer_requests_.push(callback);
 #if defined(TOOLKIT_GTK)
-    surface_refs_.insert(std::make_pair(surface_id, surface_ref));
+    if (compositing_surface.handle)
+      surface_refs_.insert(std::make_pair(surface_id, surface_ref));
 #endif
   } else {
     CreateCommandBufferError(callback, MSG_ROUTING_NONE);