cc: Implement shared worker contexts. (v1)

content/common/gpu/client/context_provider_command_buffer.h

Index: content/common/gpu/client/context_provider_command_buffer.h
diff --git a/content/common/gpu/client/context_provider_command_buffer.h b/content/common/gpu/client/context_provider_command_buffer.h
index 1e0d23f82b915609416ce8473e6d4f83d6fd24bb..8ebff943ceaebeae32208c0b5d1e3796c0baa34b 100644
--- a/content/common/gpu/client/context_provider_command_buffer.h
+++ b/content/common/gpu/client/context_provider_command_buffer.h
@@ -29,6 +29,7 @@ class CONTENT_EXPORT ContextProviderCommandBuffer
       CommandBufferContextType type);
 
   CommandBufferProxyImpl* GetCommandBufferProxy();
+  void Destroy();
 
   // cc_blink::ContextProviderWebContext implementation.
   WebGraphicsContext3DCommandBufferImpl* WebContext3D() override;
@@ -51,6 +52,7 @@ class CONTENT_EXPORT ContextProviderCommandBuffer
   void SetMemoryPolicyChangedCallback(
       const MemoryPolicyChangedCallback& memory_policy_changed_callback)
       override;
+  bool HasBeenDestroyed() override;
 
  protected:
   ContextProviderCommandBuffer(
@@ -63,6 +65,7 @@ class CONTENT_EXPORT ContextProviderCommandBuffer
 
  private:
   void InitializeCapabilities();
+  void DestroyWithMainThreadLockAcquired();
 
   base::ThreadChecker main_thread_checker_;
   base::ThreadChecker context_thread_checker_;