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

content/browser/renderer_host/render_process_host_impl.h

Index: content/browser/renderer_host/render_process_host_impl.h
diff --git a/content/browser/renderer_host/render_process_host_impl.h b/content/browser/renderer_host/render_process_host_impl.h
index ccb83b2a16c3919a1797502f44987c1c39051172..91241da5625a4e9e2c59ed40f754d8df64f69cf3 100644
--- a/content/browser/renderer_host/render_process_host_impl.h
+++ b/content/browser/renderer_host/render_process_host_impl.h
@@ -155,6 +155,8 @@ class CONTENT_EXPORT RenderProcessHostImpl
   void ResumeDeferredNavigation(const GlobalRequestID& request_id) override;
   void NotifyTimezoneChange(const std::string& timezone) override;
   ServiceRegistry* GetServiceRegistry() override;
+  scoped_ptr<base::SharedPersistentMemoryAllocator> ExtractMetricsAllocator()
+      override;
   const base::TimeTicks& GetInitTimeForNavigationMetrics() const override;
   bool SubscribeUniformEnabled() const override;
   void OnAddSubscription(unsigned int target) override;
@@ -505,6 +507,8 @@ class CONTENT_EXPORT RenderProcessHostImpl
   // Whether or not the CHROMIUM_subscribe_uniform WebGL extension is enabled
   bool subscribe_uniform_enabled_;
 
+  scoped_ptr<base::SharedPersistentMemoryAllocator> metrics_allocator_;

[Alexei Svitkine (slow), 2016/03/29 17:51:24]

Needs a comment.

[bcwhite, 2016/03/30 21:25:55]

Done.

+
   bool channel_connected_;
   bool sent_render_process_ready_;