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..98be795c52bdcc621670908b016209779a15f506 100644
--- a/ash/shell_delegate.h
+++ b/ash/shell_delegate.h
@@ -139,6 +139,9 @@ class ASH_EXPORT ShellDelegate {
 
   // Toggles the status of touchpad between enabled and disabled.
   virtual void ToggleTouchpad() {}
+
+  // Suspends all webcontents associated media sessions to stop managed players.

[Daniel Erat, 2017/05/22 23:38:34]

nit: "WebContents-associated"

[Qiang(Joe) Xu, 2017/05/23 17:54:46]

Done.

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