cros: Suspend media sessions with display off trigger by tablet power button

ash/shell_delegate.h

Index: ash/shell_delegate.h
diff --git a/ash/shell_delegate.h b/ash/shell_delegate.h
index 7a3caf47562952531fba8c24f85e0b3541da6221..73f8f7278394a289b4d96f781c8c5b9b7a834b96 100644
--- a/ash/shell_delegate.h
+++ b/ash/shell_delegate.h
@@ -139,6 +139,10 @@ class ASH_EXPORT ShellDelegate {
 
   // Toggles the status of touchpad between enabled and disabled.
   virtual void ToggleTouchpad() {}
+
+  // Resumes/Suspends media sessions systematically.

[Daniel Erat, 2017/05/17 01:22:25]

could you document what media sessions are here? it's non-obvious to me what's
included.

[Qiang(Joe) Xu, 2017/05/22 22:58:46]

Done. Media session is a name/way manage media contents to allow resume/stop
managed players.

On Chrome android, media session is an API for notification media controller.

+  virtual void ResumeMediaSessions() {}
+  virtual void SuspendMediaSessions() {}
 };
 
 }  // namespace ash