Create and pass shared-histogram-allocator from browser to renderer.

content/public/browser/render_process_host.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_BROWSER_RENDER_PROCESS_HOST_H_
 #define CONTENT_PUBLIC_BROWSER_RENDER_PROCESS_HOST_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <list>
 
 #include "base/id_map.h"
 #include "base/process/kill.h"
 #include "base/process/process_handle.h"
 #include "base/supports_user_data.h"
 #include "content/common/content_export.h"
 #include "ipc/ipc_channel_proxy.h"
 #include "ipc/ipc_sender.h"
 #include "ui/gfx/native_widget_types.h"
 
 class GURL;
 
 namespace base {
+class SharedPersistentMemoryAllocator;
 class TimeDelta;
 }
 
 namespace gpu {
 union ValueState;
 }
 
 namespace media {
 class AudioOutputController;
 class MediaKeys;
@@ skipping 216 matching lines @@
   // transferring it to a new renderer process.
   virtual void ResumeDeferredNavigation(const GlobalRequestID& request_id) = 0;
 
   // Notifies the renderer that the timezone configuration of the system might
   // have changed.
   virtual void NotifyTimezoneChange(const std::string& zone_id) = 0;
 
   // Returns the ServiceRegistry for this process.
   virtual ServiceRegistry* GetServiceRegistry() = 0;
 
+  // Extracts any persistent-memory-allocator used for renderer metrics.
+  // Ownership is passed to the caller. To support sharing of histogram data
+  // between the Renderer and the Browser, the allocator is created when the
+  // process is created and later retrieved by the SubprocessMetricsProvider
+  // for management.
+  virtual scoped_ptr<base::SharedPersistentMemoryAllocator>
+  TakeMetricsAllocator() = 0;
+
   // PlzNavigate
   // Returns the time the first call to Init completed successfully (after a new
   // renderer process was created); further calls to Init won't change this
   // value.
   // Note: Do not use! Will disappear after PlzNavitate is completed.
   virtual const base::TimeTicks& GetInitTimeForNavigationMetrics() const = 0;
 
   // Returns whether or not the CHROMIUM_subscribe_uniform WebGL extension
   // is currently enabled
   virtual bool SubscribeUniformEnabled() const = 0;
@@ skipping 86 matching lines @@
   static void SetMaxRendererProcessCount(size_t count);
 
   // Returns the current maximum number of renderer process hosts kept by the
   // content module.
   static size_t GetMaxRendererProcessCount();
 };
 
 }  // namespace content.
 
 #endif  // CONTENT_PUBLIC_BROWSER_RENDER_PROCESS_HOST_H_