Create system tray item for accessing chrome://slow

ash/system/chromeos/tray_tracing.h

Index: ash/system/chromeos/tray_tracing.h
diff --git a/ash/system/chromeos/tray_tracing.h b/ash/system/chromeos/tray_tracing.h
new file mode 100644
index 0000000000000000000000000000000000000000..f9491e1d90319dd1595a15eba32f8527545d94ff
--- /dev/null
+++ b/ash/system/chromeos/tray_tracing.h
@@ -0,0 +1,57 @@
+// Copyright 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef ASH_SYSTEM_TRAY_TRACING_H_
+#define ASH_SYSTEM_TRAY_TRACING_H_
+
+#include "ash/ash_export.h"
+#include "ash/system/tray/tray_image_item.h"
+
+namespace views {
+class View;
+}
+
+namespace ash {
+
+class ASH_EXPORT TracingObserver {
+ public:
+  virtual ~TracingObserver() {}
+
+  // Notifies when tracing mode changes.
+  virtual void OnTracingModeChanged(bool value) = 0;
+};
+
+namespace internal {
+
+// This is the item that displays when users enable performance tracing at
+// chrome://slow.  It alerts them that this mode is running, and provides an
+// easy way to open the page to disable it.
+class TrayTracing : public TrayImageItem,
+                    public TracingObserver {
+ public:
+  explicit TrayTracing(SystemTray* system_tray);
+  virtual ~TrayTracing();
+
+ private:
+  void SetTrayIconVisible(bool visible);
+
+  // Overridden from TrayImageItem.
+  virtual bool GetInitialVisibility() OVERRIDE;
+  virtual views::View* CreateDefaultView(user::LoginStatus status) OVERRIDE;
+  virtual views::View* CreateDetailedView(user::LoginStatus status) OVERRIDE;
+  virtual void DestroyDefaultView() OVERRIDE;
+  virtual void DestroyDetailedView() OVERRIDE;
+
+  // Overridden from TracingObserver.
+  virtual void OnTracingModeChanged(bool value) OVERRIDE;
+
+  views::View* default_;
+
+  DISALLOW_COPY_AND_ASSIGN(TrayTracing);
+};
+
+}  // namespace internal
+}  // namespace ash
+
+#endif  // ASH_SYSTEM_TRAY_TRACING_H_