Free worker context resources on idle.

gpu/command_buffer/client/gles2_implementation.h

Index: gpu/command_buffer/client/gles2_implementation.h
diff --git a/gpu/command_buffer/client/gles2_implementation.h b/gpu/command_buffer/client/gles2_implementation.h
index b997ea13f1b44c9edd7156360371c1ab23174da2..2a966fa2494472b4b003115adfa5283e85629925 100644
--- a/gpu/command_buffer/client/gles2_implementation.h
+++ b/gpu/command_buffer/client/gles2_implementation.h
@@ -212,6 +212,10 @@ class GLES2_IMPL_EXPORT GLES2Implementation
       std::unique_ptr<ScopedVisibility> visibility) override;
   bool AnyClientsVisible() const override;
 
+  std::unique_ptr<ScopedBusy> ClientBecameBusy() override;
+  void ClientBecameNotBusy(std::unique_ptr<ScopedBusy> busy) override;
+  void SetIdleCallback(const base::Closure& callback) override;
+
   // TODO(danakj): Move to ContextSupport once ContextProvider doesn't need to
   // intercept it.
   void SetLostContextCallback(const base::Closure& callback);
@@ -696,6 +700,9 @@ class GLES2_IMPL_EXPORT GLES2Implementation
 
   PixelStoreParams GetUnpackParameters(Dimension dimension);
 
+  void RunIdleCallback(uint32_t callback_generation) const;
+  void CancelIdleCallback();
+
   GLES2Util util_;
   GLES2CmdHelper* helper_;
   TransferBufferInterface* transfer_buffer_;
@@ -823,10 +830,19 @@ class GLES2_IMPL_EXPORT GLES2Implementation
   base::Closure lost_context_callback_;
   bool lost_context_callback_run_ = false;
 
+  // |idle_lock_| must be held while accessing |idle_callback_|, |is_idle_| or
+  // |current_idle_callback_generation_|.
+  mutable base::Lock idle_lock_;
+  base::Closure idle_callback_;
+  bool is_idle_ = true;
+  uint32_t current_idle_callback_generation_ = 0;
+
   int current_trace_stack_;
 
   GpuControl* gpu_control_;
 
+  scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
+
   Capabilities capabilities_;
 
   // Flag to indicate whether the implementation can retain resources, or