Initial implementation for sharing field trial state (win)

content/browser/renderer_host/render_process_host_impl.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_BROWSER_RENDERER_HOST_RENDER_PROCESS_HOST_IMPL_H_
 #define CONTENT_BROWSER_RENDERER_HOST_RENDER_PROCESS_HOST_IMPL_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 318 matching lines @@
       mojo::InterfaceRequest<mojom::StoragePartitionService> request);
 
   // Control message handlers.
   void OnShutdownRequest();
   void SuddenTerminationChanged(bool enabled);
   void OnUserMetricsRecordAction(const std::string& action);
   void OnCloseACK(int old_route_id);
 
   // Generates a command line to be used to spawn a renderer and appends the
   // results to |*command_line|.
-  void AppendRendererCommandLine(base::CommandLine* command_line) const;
+  void AppendRendererCommandLine(base::CommandLine* command_line);
 
   // Copies applicable command line switches from the given |browser_cmd| line
   // flags to the output |renderer_cmd| line flags. Not all switches will be
   // copied over.
   void PropagateBrowserCommandLineToRenderer(
       const base::CommandLine& browser_cmd,
-      base::CommandLine* renderer_cmd) const;
+      base::CommandLine* renderer_cmd);
 
   // Inspects the current object state and sets/removes background priority if
   // appropriate. Should be called after any of the involved data members
   // change.
   void UpdateProcessPriority();
 
   // Creates a PersistentMemoryAllocator and shares it with the renderer
   // process for it to store histograms from that process. The allocator is
   // available for extraction by a SubprocesMetricsProvider in order to
   // report those histograms to UMA.
@@ skipping 193 matching lines @@
   // for UMA.
   size_t max_worker_count_;
 
   // Context shared for each mojom::PermissionService instance created for this
   // RPH.
   std::unique_ptr<PermissionServiceContext> permission_service_context_;
 
   // The memory allocator, if any, in which the renderer will write its metrics.
   std::unique_ptr<base::SharedPersistentMemoryAllocator> metrics_allocator_;
 
+  // Anonymous shared memory segment to share with subprocess containing list of
+  // field trials (represented as a string).
+  // TODO(lawrencewu): Eventually remove this and use single shared memory
+  // object across processes.

[Alexei Svitkine (slow), 2016/10/06 21:39:28]

Suggest filing a crbug for this later work and referencing it in this comment.
Same for the other place you have this TODO.

[lawrencewu, 2016/10/07 15:07:21]

Done: crbug.com/653874

+  std::unique_ptr<base::SharedMemory> field_trial_state_;
+
   bool channel_connected_;
   bool sent_render_process_ready_;
 
 #if defined(OS_ANDROID)
   // UI thread is the source of sync IPCs and all shutdown signals.
   // Therefore a proper shutdown event to unblock the UI thread is not
   // possible without massive refactoring shutdown code.
   // Luckily Android never performs a clean shutdown. So explicitly
   // ignore this problem.
   base::WaitableEvent never_signaled_;
 #endif
 
   scoped_refptr<ResourceMessageFilter> resource_message_filter_;
 
   mojom::RouteProviderAssociatedPtr remote_route_provider_;
 
   // A WeakPtrFactory which is reset every time Cleanup() runs. Used to vend
   // WeakPtrs which are invalidated any time the RPHI is recycled.
   std::unique_ptr<base::WeakPtrFactory<RenderProcessHostImpl>>
       instance_weak_factory_;
 
   base::WeakPtrFactory<RenderProcessHostImpl> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderProcessHostImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_RENDER_PROCESS_HOST_IMPL_H_