Update Context Client Visibility to use Scoped Pattern

gpu/command_buffer/client/context_support.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef GPU_COMMAND_BUFFER_CLIENT_CONTEXT_SUPPORT_H_
 #define GPU_COMMAND_BUFFER_CLIENT_CONTEXT_SUPPORT_H_
 
 #include <stdint.h>
 
 #include "base/callback.h"
 #include "ui/gfx/overlay_transform.h"
 
 namespace gfx {
 class Rect;
 class RectF;
 }
 
 namespace gpu {
 
+class ScopedContextClientVisibility;

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

remove?

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

Done.

 struct SyncToken;
 
 class ContextSupport {
  public:
   // Runs |callback| when a sync token is signalled.
   virtual void SignalSyncToken(const SyncToken& sync_token,
                                const base::Closure& callback) = 0;
 
   // Runs |callback| when a query created via glCreateQueryEXT() has cleared
   // passed the glEndQueryEXT() point.
@@ skipping 19 matching lines @@
                                     const gfx::RectF& uv_rect) = 0;
 
   // Returns an ID that can be used to globally identify the share group that
   // this context's resources belong to.
   virtual uint64_t ShareGroupTracingGUID() const = 0;
 
   // Sets a callback to be run when an error occurs.
   virtual void SetErrorMessageCallback(
       const base::Callback<void(const char*, int32_t)>& callback) = 0;
 
-  // Called when a client of the context has changed visibility.
-  virtual void SetClientVisible(int client_id, bool is_visible) = 0;
+  class ScopedVisibility {};
+  virtual std::unique_ptr<ScopedVisibility> ClientBecameVisible() = 0;
+  virtual void ClientBecameNotVisible(
+      std::unique_ptr<ScopedVisibility> visibility) = 0;
   virtual bool AnyClientsVisible() const = 0;
 
  protected:
   ContextSupport() {}
   virtual ~ContextSupport() {}
 };
 
 }
 
 #endif  // GPU_COMMAND_BUFFER_CLIENT_CONTEXT_SUPPORT_H_