Mojoify PoweMonitorMessageBroadcaster IPC from browser to child process

content/child/power_monitor_broadcast_source.h

 // Copyright (c) 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_CHILD_POWER_MONITOR_BROADCAST_SOURCE_H_
 #define CONTENT_CHILD_POWER_MONITOR_BROADCAST_SOURCE_H_
 
 #include "base/macros.h"
 #include "base/power_monitor/power_monitor_source.h"
 #include "content/common/content_export.h"
-#include "ipc/ipc_channel.h"
-
-namespace IPC {
-class MessageFilter;
-}
+#include "device/power_monitor/public/interfaces/power_monitor.mojom.h"
+#include "mojo/public/cpp/bindings/binding.h"
 
 namespace content {
 
-class PowerMessageFilter;
-
 // Receives Power Monitor IPC messages sent from the browser process and relays
 // them to the PowerMonitor of the current process.
-class CONTENT_EXPORT PowerMonitorBroadcastSource :
-    public base::PowerMonitorSource {
+class CONTENT_EXPORT PowerMonitorBroadcastSource
+    : public base::PowerMonitorSource,
+      NON_EXPORTED_BASE(public device::mojom::PowerMonitorClient) {
  public:
   explicit PowerMonitorBroadcastSource();
   ~PowerMonitorBroadcastSource() override;
 
-  IPC::MessageFilter* GetMessageFilter();
+  void PowerStateChange(bool on_battery_power) override;
+  void Suspend() override;
+  void Resume() override;
 
  private:
-  friend class PowerMessageFilter;
-
   bool IsOnBatteryPowerImpl() override;
-
-  void OnPowerStateChange(bool on_battery_power);
-  void OnSuspend();
-  void OnResume();
-
   bool last_reported_battery_power_state_;
-  scoped_refptr<PowerMessageFilter> message_filter_;
+  mojo::Binding<device::mojom::PowerMonitorClient> binding_;

[blundell, 2016/10/25 16:53:44]

This can be just a StrongBinding and ChildThreadImpl doesn't have to own this
object anymore.

[ke.he, 2016/10/26 10:01:51]

@blundell, Big thanks for your comments:)
Here the ChildThreadImpl doesn't directly own this object, ChildThreadImpl owns
power_monitor_ (std::unique_ptr<base::PowerMonitor>), then power_monitor_ owns
this object. From the current code logic, the lifetime of this
PowerMonitorBroadcastSource object is same as the ChildThreadImpl, so the
StrongBinding lost its meanings in this scenario. It seems the "common" Binding
is also acceptable here.  How do you think about this? Thanks again!

[blundell, 2016/10/26 16:18:02]

Thanks for the clarification. The current structure makes sense.

 
   DISALLOW_COPY_AND_ASSIGN(PowerMonitorBroadcastSource);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_CHILD_POWER_MONITOR_BROADCAST_SOURCE_H_