Remove dead flush histograms code.

content/public/test/mock_render_thread.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 CONTENT_PUBLIC_TEST_MOCK_RENDER_THREAD_H_
 #define CONTENT_PUBLIC_TEST_MOCK_RENDER_THREAD_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 59 matching lines @@
   void RecordComputedAction(const std::string& action) override;
   std::unique_ptr<base::SharedMemory> HostAllocateSharedMemoryBuffer(
       size_t buffer_size) override;
   cc::SharedBitmapManager* GetSharedBitmapManager() override;
   void RegisterExtension(v8::Extension* extension) override;
   void ScheduleIdleHandler(int64_t initial_delay_ms) override;
   void IdleHandler() override;
   int64_t GetIdleNotificationDelayInMs() const override;
   void SetIdleNotificationDelayInMs(
       int64_t idle_notification_delay_in_ms) override;
-  void UpdateHistograms(int sequence_number) override;
   int PostTaskToAllWebWorkers(const base::Closure& closure) override;
   bool ResolveProxy(const GURL& url, std::string* proxy_list) override;
   base::WaitableEvent* GetShutdownEvent() override;
 #if defined(OS_WIN)
   void PreCacheFont(const LOGFONT& log_font) override;
   void ReleaseCachedFonts() override;
 #endif
   ServiceManagerConnection* GetServiceManagerConnection() override;
   service_manager::InterfaceRegistry* GetInterfaceRegistry() override;
   service_manager::InterfaceProvider* GetRemoteInterfaces() override;
@@ skipping 75 matching lines @@
   std::unique_ptr<service_manager::InterfaceProvider> remote_interfaces_;
   service_manager::mojom::InterfaceProviderRequest
       pending_remote_interface_provider_request_;
 
   std::unique_ptr<mojom::RenderMessageFilter> mock_render_message_filter_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_TEST_MOCK_RENDER_THREAD_H_