Update Context Client Visibility to use Scoped Pattern

gpu/command_buffer/client/gles2_implementation.h

 // Copyright (c) 2012 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_GLES2_IMPLEMENTATION_H_
 #define GPU_COMMAND_BUFFER_CLIENT_GLES2_IMPLEMENTATION_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 188 matching lines @@
   void PartialSwapBuffers(const gfx::Rect& sub_buffer) override;
   void CommitOverlayPlanes() override;
   void ScheduleOverlayPlane(int plane_z_order,
                             gfx::OverlayTransform plane_transform,
                             unsigned overlay_texture_id,
                             const gfx::Rect& display_bounds,
                             const gfx::RectF& uv_rect) override;
   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
   // intercept it.
   void SetLostContextCallback(const base::Closure& callback);
 
   void GetProgramInfoCHROMIUMHelper(GLuint program,
                                     std::vector<int8_t>* result);
   GLint GetAttribLocationHelper(GLuint program, const char* name);
   GLint GetUniformLocationHelper(GLuint program, const char* name);
@@ skipping 601 matching lines @@
   bool lost_context_callback_run_ = false;
 
   int current_trace_stack_;
 
   GpuControl* gpu_control_;
 
   Capabilities capabilities_;
 
   // Flag to indicate whether the implementation can retain resources, or
   // whether it should aggressively free them.
-  bool aggressively_free_resources_;
+  bool aggressively_free_resources_ = false;
 
-  // The set of IDs of all visible clients.
-  std::set<int> visible_clients_;
+  uint32_t num_visible_clients_ = 0;
 
   // Result of last GetString(GL_EXTENSIONS), used to keep
   // GetString(GL_EXTENSIONS), GetStringi(GL_EXTENSIONS, index) and
   // GetIntegerv(GL_NUM_EXTENSIONS) in sync. This points to gl_strings, valid
   // forever.
   const char* cached_extension_string_;
 
   // Populated if cached_extension_string_ != nullptr. These point to
   // gl_strings, valid forever.
   std::vector<const char*> cached_extensions_;
@@ skipping 38 matching lines @@
 
 inline bool GLES2Implementation::GetTexParameterivHelper(
     GLenum /* target */, GLenum /* pname */, GLint* /* params */) {
   return false;
 }
 
 }  // namespace gles2
 }  // namespace gpu
 
 #endif  // GPU_COMMAND_BUFFER_CLIENT_GLES2_IMPLEMENTATION_H_