Add logging for slow device events, limit network UI update rate

ash/system/chromeos/network/tray_network.h

Index: ash/system/chromeos/network/tray_network.h
diff --git a/ash/system/chromeos/network/tray_network.h b/ash/system/chromeos/network/tray_network.h
index 407b64e52714307c90352be24c2f0e1da9e17794..72c0a0914a4168475fb306905af36cfd4c20c5af 100644
--- a/ash/system/chromeos/network/tray_network.h
+++ b/ash/system/chromeos/network/tray_network.h
@@ -31,32 +31,28 @@ class TrayNetwork : public SystemTrayItem,
                     public TrayNetworkStateObserver::Delegate {
  public:
   explicit TrayNetwork(SystemTray* system_tray);
-  virtual ~TrayNetwork();
+  ~TrayNetwork() override;
 
   tray::NetworkDetailedView* detailed() { return detailed_; }
 
   // SystemTrayItem
-  virtual views::View* CreateTrayView(user::LoginStatus status) override;
-  virtual views::View* CreateDefaultView(user::LoginStatus status) override;
-  virtual views::View* CreateDetailedView(user::LoginStatus status) override;
-  virtual void DestroyTrayView() override;
-  virtual void DestroyDefaultView() override;
-  virtual void DestroyDetailedView() override;
-  virtual void UpdateAfterLoginStatusChange(user::LoginStatus status) override;
-  virtual void UpdateAfterShelfAlignmentChange(
-      ShelfAlignment alignment) override;
+  views::View* CreateTrayView(user::LoginStatus status) override;
+  views::View* CreateDefaultView(user::LoginStatus status) override;
+  views::View* CreateDetailedView(user::LoginStatus status) override;
+  void DestroyTrayView() override;
+  void DestroyDefaultView() override;
+  void DestroyDetailedView() override;
+  void UpdateAfterLoginStatusChange(user::LoginStatus status) override;
+  void UpdateAfterShelfAlignmentChange(ShelfAlignment alignment) override;
 
   // NetworkObserver
-  virtual void RequestToggleWifi() override;
+  void RequestToggleWifi() override;
 
   // NetworkPortalDetectorObserver
-  virtual void OnCaptivePortalDetected(
-      const std::string& service_path) override;
+  void OnCaptivePortalDetected(const std::string& service_path) override;
 
   // TrayNetworkStateObserver::Delegate
-  virtual void NetworkStateChanged(bool list_changed) override;
-  virtual void NetworkServiceChanged(
-      const chromeos::NetworkState* network) override;
+  void NetworkStateChanged() override;
 
  private:
   tray::NetworkTrayView* tray_;