arc-bridge: Start ArcBridgeService on session start

chrome/browser/ui/ash/chrome_shell_delegate.h

Index: chrome/browser/ui/ash/chrome_shell_delegate.h
diff --git a/chrome/browser/ui/ash/chrome_shell_delegate.h b/chrome/browser/ui/ash/chrome_shell_delegate.h
index e069b716c781e133de0fe778e1012b8bc8453b99..fdb281b3917ba9eb30f4ffa61d8dcfd89d5bf578 100644
--- a/chrome/browser/ui/ash/chrome_shell_delegate.h
+++ b/chrome/browser/ui/ash/chrome_shell_delegate.h
@@ -17,6 +17,10 @@
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 
+#if defined(OS_CHROMEOS)
+#include "ash/shell_observer.h"
+#endif
+
 class Browser;
 
 namespace ash {
@@ -103,6 +107,22 @@ class ChromeShellDelegate : public ash::ShellDelegate,
 #if defined(OS_CHROMEOS)
   scoped_ptr<chromeos::DisplayConfigurationObserver>
       display_configuration_observer_;
+
+  // An Observer to track session state and start/stop ARC accordingly.
+  class ArcSessionObserver : public ash::ShellObserver {
+   public:
+    ArcSessionObserver();
+    ~ArcSessionObserver() override;
+
+    // ash::ShellObserver overrides:
+    void OnLoginStateChanged(ash::user::LoginStatus status) override;
+
+   private:
+    DISALLOW_COPY_AND_ASSIGN(ArcSessionObserver);
+  };
+
+  // An Observer to track session state and start/stop ARC accordingly.
+  scoped_ptr<ArcSessionObserver> arc_session_observer_;
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(ChromeShellDelegate);