Add optimization for CHROMIUM_subscribe_uniform extension.

content/browser/renderer_host/render_process_host_impl.h

Index: content/browser/renderer_host/render_process_host_impl.h
diff --git a/content/browser/renderer_host/render_process_host_impl.h b/content/browser/renderer_host/render_process_host_impl.h
index 9175a2c6c0dfa9cb58ad3bd60e59bd9a8347543e..690ccef2b4ee079989385e6a42d7e5441874ac18 100644
--- a/content/browser/renderer_host/render_process_host_impl.h
+++ b/content/browser/renderer_host/render_process_host_impl.h
@@ -33,6 +33,10 @@ namespace gfx {
 class Size;
 }
 
+namespace gpu {
+class ValueStateMap;
+}
+
 namespace IPC {
 class ChannelMojoHost;
 }
@@ -140,6 +144,11 @@ class CONTENT_EXPORT RenderProcessHostImpl
   void NotifyTimezoneChange() override;
   ServiceRegistry* GetServiceRegistry() override;
   const base::TimeTicks& GetInitTimeForNavigationMetrics() const override;
+  bool SubscribeUniformEnabled() const override;
+  void OnAddSubscription(unsigned int target) override;
+  void OnRemoveSubscription(unsigned int target) override;
+  void SendUpdateValueState(
+      unsigned int target, const gpu::ValueState& state) override;
 
   // IPC::Sender via RenderProcessHost.
   bool Send(IPC::Message* msg) override;
@@ -470,6 +479,20 @@ class CONTENT_EXPORT RenderProcessHostImpl
   // Context shared for each PermissionService instance created for this RPH.
   scoped_ptr<PermissionServiceContext> permission_service_context_;
 
+  // This is a set of all subscription targets valuebuffers in the GPU process
+  // are currently subscribed too. Used to prevent sending unnecessary
+  // ValueState updates.
+  typedef base::hash_set<unsigned int> SubscriptionSet;
+  SubscriptionSet subscription_set_;
+
+  // Maintains ValueStates which are not currently subscribed too so we can
+  // pass them to the GpuService if a Valuebuffer ever subscribes to the
+  // respective subscription target
+  scoped_refptr<gpu::ValueStateMap> pending_valuebuffer_state_;
+
+  // Whether or not the CHROMIUM_subscribe_uniform WebGL extension is enabled
+  bool subscribe_uniform_enabled_;
+
   base::WeakPtrFactory<RenderProcessHostImpl> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderProcessHostImpl);