Mojoify PoweMonitorMessageBroadcaster IPC from browser to child process

content/browser/power_monitor_message_broadcaster.h

 // Copyright 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 CONTENT_BROWSER_POWER_MONITOR_MESSAGE_BROADCASTER_H_
 #define CONTENT_BROWSER_POWER_MONITOR_MESSAGE_BROADCASTER_H_
 
 #include "base/macros.h"
 #include "base/power_monitor/power_observer.h"
 #include "content/common/content_export.h"
-
-namespace IPC {
-class Sender;
-}
+#include "device/power_monitor/public/interfaces/power_monitor.mojom.h"
 
 namespace content {
 
 // A class used to monitor the power state change and communicate it to child
 // processes via IPC.
 class CONTENT_EXPORT PowerMonitorMessageBroadcaster
     : public base::PowerObserver {
  public:
-  explicit PowerMonitorMessageBroadcaster(IPC::Sender* sender);
+  explicit PowerMonitorMessageBroadcaster();
   ~PowerMonitorMessageBroadcaster() override;
 
   // Implement PowerObserver.
   void OnPowerStateChange(bool on_battery_power) override;
   void OnSuspend() override;
   void OnResume() override;
 
-  void Init();
+  void Init(device::mojom::PowerMonitorClientPtr& power_monitor_client);

[blundell, 2016/10/20 22:42:22]

You can do this communication via mojo, i.e.:

Add have a PowerMonitor interface that has a SetClient(PowerMontiorClient)
method.

Then you don't need to do the configuration in {child,
render}_process_host_impl.cc.

You can make PowerMonitorMessageBroadcaster be strongly bound to its binding to
handle lifetime.

[ke.he, 2016/10/24 06:54:39]

Yes it's better to add a "SetClient(PowerMontiorClient)" in mojo interface to
avoid do configurations through Init().
The problem I met is that currently there is no "RegisterMojoInterfaces
functionality" in BrowserChildProcessHostImpl. But we found a similar reference:
there is "GpuProcessHost::ConnectionFilterImpl", and it was added into
ServiceManagerConnection in GpuProcessHost::Init(). I think it is a good
reference to our scenario.
So I plan to add a "BrowserChildProcessHost::ConnectionFilterImpl" to enable the
"mojo interface register" first. Then we can register the "SetClient".
@blundell, @rockot Any comments on this? Thanks!

[ke.he, 2016/10/24 11:32:02]

Sorry the uploaded cl is branched, the latest one is at
https://codereview.chromium.org/2447613004/ 

 
  private:
-  IPC::Sender* sender_;
+  device::mojom::PowerMonitorClientPtr power_monitor_client_;
 
   DISALLOW_COPY_AND_ASSIGN(PowerMonitorMessageBroadcaster);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_POWER_MONITOR_MESSAGE_BROADCASTER_H_