mac: Expose keychain access frequency to Telemetry.

base/mac/keychain_metrics.h

+// Copyright 2014 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 BASE_MAC_KEYCHAIN_METRICS_H_
+#define BASE_MAC_KEYCHAIN_METRICS_H_
+
+#include "base/base_export.h"
+
+namespace base {
+namespace mac {
+
+// Adds an entry to a local histogram to indicate that the keychain was
+// accessed. This function should be called each time the keychain is accessed
+// so that the number of entries in the histogram corresponds to the number of
+// times that the keychain is accessed. This local histogram is used by
+// Telemetry to track the number of times the keychain is accessed.
+BASE_EXPORT void IncrementKeychainAccessHistogram();

[Lei Zhang, 2014/12/15 22:27:02]

How about moving this to crypto/apple_keychain.h ? components/os_crypt/ can
access crypto/.

[erikchen, 2014/12/15 23:16:10]

Good suggestion. I moved all histogram emission into mock_apple_keychain.

+
+}  // namespace mac
+}  // namespace base
+
+#endif  // BASE_MAC_KEYCHAIN_METRICS_H_