cros: Suspend media sessions on SuspendImminent

ash/system/power/power_event_observer.h

Index: ash/system/power/power_event_observer.h
diff --git a/ash/system/power/power_event_observer.h b/ash/system/power/power_event_observer.h
index 63365b6792828b4e68aa7808cb44d77999ca5bee..839cdd6b647772134af2eaa94fc1dd38d65e29c7 100644
--- a/ash/system/power/power_event_observer.h
+++ b/ash/system/power/power_event_observer.h
@@ -23,10 +23,7 @@ class ASH_EXPORT PowerEventObserver
   PowerEventObserver();
   ~PowerEventObserver() override;
 
-  // Called by the WebUIScreenLocker when all the lock screen animations have
-  // completed.  This really should be implemented via an observer but since
-  // ash/ isn't allowed to depend on chrome/ we need to have the
-  // WebUIScreenLocker reach into ash::Shell to make this call.
+  // Called when all the lock screen animations have completed.
   void OnLockAnimationsComplete();
 
   // chromeos::PowerManagerClient::Observer overrides:
@@ -39,10 +36,10 @@ class ASH_EXPORT PowerEventObserver
   void ScreenIsUnlocked() override;
 
   // Is the screen currently locked?
-  bool screen_locked_;
+  bool screen_locked_ = false;
 
   // Have the lock screen animations completed?
-  bool waiting_for_lock_screen_animations_;
+  bool waiting_for_lock_screen_animations_ = false;
 
   // If set, called when the lock screen animations have completed to confirm
   // that the system is ready to be suspended.