Add optimization for CHROMIUM_subscribe_uniform extension.

content/browser/gpu/gpu_process_host_ui_shim.cc

Index: content/browser/gpu/gpu_process_host_ui_shim.cc
diff --git a/content/browser/gpu/gpu_process_host_ui_shim.cc b/content/browser/gpu/gpu_process_host_ui_shim.cc
index 2293e745892609f8391e4d01e628cbc4bfc83abb..f4612c31dfc4ca3fe9bde9bbd96c7c0c540d46fe 100644
--- a/content/browser/gpu/gpu_process_host_ui_shim.cc
+++ b/content/browser/gpu/gpu_process_host_ui_shim.cc
@@ -23,6 +23,7 @@
 #include "content/browser/renderer_host/render_widget_host_view_base.h"
 #include "content/common/gpu/gpu_messages.h"
 #include "content/public/browser/browser_thread.h"
+#include "content/public/browser/render_widget_host_iterator.h"
 
 #if defined(OS_MACOSX)
 #include "ui/accelerated_widget_mac/accelerated_widget_mac.h"
@@ -230,6 +231,8 @@ bool GpuProcessHostUIShim::OnControlMessageReceived(
                         OnVideoMemoryUsageStatsReceived);
     IPC_MESSAGE_HANDLER(GpuHostMsg_ResourcesRelinquished,
                         OnResourcesRelinquished)
+    IPC_MESSAGE_HANDLER(GpuHostMsg_AddSubscription, OnAddSubscription);
+    IPC_MESSAGE_HANDLER(GpuHostMsg_RemoveSubscription, OnRemoveSubscription);
 
     IPC_MESSAGE_UNHANDLED_ERROR()
   IPC_END_MESSAGE_MAP()
@@ -306,4 +309,30 @@ void GpuProcessHostUIShim::OnResourcesRelinquished() {
   }
 }
 
+void GpuProcessHostUIShim::OnAddSubscription(
+    int32 process_id, unsigned int target) {
+  scoped_ptr<RenderWidgetHostIterator> rwhi_iterator =
+      RenderWidgetHostImpl::GetRenderWidgetHosts();
+  while (RenderWidgetHost* widget = rwhi_iterator->GetNextHost()) {
+    // Count only RenderWidgetHosts in this process.
+    if (widget->GetProcess()->GetID() == process_id) {
+      RenderWidgetHostImpl* rwhi = RenderWidgetHostImpl::From(widget);
+      rwhi->OnAddSubscription(target);
+    }
+  }
+}
+
+void GpuProcessHostUIShim::OnRemoveSubscription(
+    int32 process_id, unsigned int target) {
+  scoped_ptr<RenderWidgetHostIterator> rwhi_iterator =
+      RenderWidgetHostImpl::GetRenderWidgetHosts();
+  while (RenderWidgetHost* widget = rwhi_iterator->GetNextHost()) {
+    // Count only RenderWidgetHosts in this process.
+    if (widget->GetProcess()->GetID() == process_id) {
+      RenderWidgetHostImpl* rwhi = RenderWidgetHostImpl::From(widget);
+      rwhi->OnRemoveSubscription(target);
+    }
+  }
+}
+
 }  // namespace content