Remove ContextProvider::IsContextLost.

ui/compositor/test/in_process_context_provider.h

 // Copyright (c) 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 UI_COMPOSITOR_TEST_IN_PROCESS_CONTEXT_PROVIDER_H_
 #define UI_COMPOSITOR_TEST_IN_PROCESS_CONTEXT_PROVIDER_H_
 
 #include <string>
 
 #include "base/macros.h"
@@ skipping 41 matching lines @@
 
   // cc::ContextProvider:
   bool BindToCurrentThread() override;
   Capabilities ContextCapabilities() override;
   gpu::gles2::GLES2Interface* ContextGL() override;
   gpu::ContextSupport* ContextSupport() override;
   class GrContext* GrContext() override;
   void InvalidateGrContext(uint32_t state) override;
   void SetupLock() override;
   base::Lock* GetLock() override;
-  bool IsContextLost() override;
   void VerifyContexts() override;
   void DeleteCachedResources() override;
   bool DestroyedOnMainThread() override;
   void SetLostContextCallback(
       const LostContextCallback& lost_context_callback) override;
   void SetMemoryPolicyChangedCallback(
       const MemoryPolicyChangedCallback& memory_policy_changed_callback)
       override;
 
   void OnLostContext();
@@ skipping 18 matching lines @@
   bool destroyed_;
 
   base::Lock context_lock_;
 
   DISALLOW_COPY_AND_ASSIGN(InProcessContextProvider);
 };
 
 }  // namespace ui
 
 #endif  // UI_COMPOSITOR_TEST_IN_PROCESS_CONTEXT_PROVIDER_H_