Added the Ash.Tab.TimeBetweenSwitchToExistingTabUserActions histogram to track time between tab swit

ash/metrics/user_metrics_recorder_proxy.h

Index: ash/metrics/user_metrics_recorder_proxy.h
diff --git a/ash/metrics/user_metrics_recorder_proxy.h b/ash/metrics/user_metrics_recorder_proxy.h
new file mode 100644
index 0000000000000000000000000000000000000000..1612dca9f4c2b2f6af4d05fc74d7f22300438cbd
--- /dev/null
+++ b/ash/metrics/user_metrics_recorder_proxy.h
@@ -0,0 +1,22 @@
+// Copyright 2015 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_METRICS_USER_METRICS_RECORDER_PROXY_H_
+#define ASH_METRICS_USER_METRICS_RECORDER_PROXY_H_
+
+#include <string>
+
+#include "ash/ash_export.h"
+#include "base/macros.h"
+
+namespace ash {
+
+class ASH_EXPORT UserMetricsRecorderProxy {

[oshima, 2015/05/15 17:13:36]

you can call ash/metrics from chrome/browser/ui/ash, so you don't need extra
proxy.

[bruthig, 2015/05/15 19:11:27]

Done.

+ public:
+  virtual ~UserMetricsRecorderProxy() {}
+};
+
+}  // namespace ash
+
+#endif  // ASH_METRICS_USER_METRICS_RECORDER_PROXY_H_