Update Context Client Visibility to use Scoped Pattern

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 48e5dbf8d3a55ec80c76f1093b32b1d64779eb4c..b5caceffe0ae7e6f3cef098ef2f99ec239d05c86 100644
--- a/gpu/command_buffer/client/gles2_implementation.h
+++ b/gpu/command_buffer/client/gles2_implementation.h
@@ -206,7 +206,9 @@ class GLES2_IMPL_EXPORT GLES2Implementation
   uint64_t ShareGroupTracingGUID() const override;
   void SetErrorMessageCallback(
       const base::Callback<void(const char*, int32_t)>& callback) override;
-  void SetClientVisible(int client_id, bool is_visible) override;
+  std::unique_ptr<ScopedVisibility> ClientBecameVisible() override;
+  void ClientBecameNotVisible(
+      std::unique_ptr<ScopedVisibility> visibility) override;
   bool AnyClientsVisible() const override;
 
   // TODO(danakj): Move to ContextSupport once ContextProvider doesn't need to
@@ -830,8 +832,8 @@ class GLES2_IMPL_EXPORT GLES2Implementation
   // whether it should aggressively free them.
   bool aggressively_free_resources_;
 
-  // The set of IDs of all visible clients.
-  std::set<int> visible_clients_;
+  // The number of visible clients.
+  uint32_t visible_clients_;

[danakj, 2016/08/18 21:39:44]

num_visible_clients_?

[ericrk, 2016/08/19 17:23:19]

Done.

 
   // Result of last GetString(GL_EXTENSIONS), used to keep
   // GetString(GL_EXTENSIONS), GetStringi(GL_EXTENSIONS, index) and