Putting histogram names of tracked prefs in tracked_preference_histogram_name file.

components/user_prefs/tracked/tracked_preference_histogram_names.cc

Index: components/user_prefs/tracked/tracked_preference_histogram_names.cc
diff --git a/components/user_prefs/tracked/tracked_preference_histogram_names.cc b/components/user_prefs/tracked/tracked_preference_histogram_names.cc
new file mode 100644
index 0000000000000000000000000000000000000000..fe9794b8502d355d6e9bd16216f0ec1752b82149
--- /dev/null
+++ b/components/user_prefs/tracked/tracked_preference_histogram_names.cc
@@ -0,0 +1,28 @@
+// 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.
+
+#include "components/user_prefs/tracked/tracked_preference_histogram_names.h"
+
+namespace tracked_pref_histogram_names {
+
+// Tracked pref histogram names.
+const char kTrackedPrefHistogramUnchanged[] =
+    "Settings.TrackedPreferenceUnchanged";
+const char kTrackedPrefHistogramCleared[] = "Settings.TrackedPreferenceCleared";
+const char kTrackedPrefHistogramMigratedLegacyDeviceId[] =
+    "Settings.TrackedPreferenceMigratedLegacyDeviceId";
+const char kTrackedPrefHistogramChanged[] = "Settings.TrackedPreferenceChanged";
+const char kTrackedPrefHistogramInitialized[] =
+    "Settings.TrackedPreferenceInitialized";
+const char kTrackedPrefHistogramTrustedInitialized[] =
+    "Settings.TrackedPreferenceTrustedInitialized";
+const char kTrackedPrefHistogramNullInitialized[] =
+    "Settings.TrackedPreferenceNullInitialized";
+const char kTrackedPrefHistogramWantedReset[] =
+    "Settings.TrackedPreferenceWantedReset";
+const char kTrackedPrefHistogramReset[] = "Settings.TrackedPreferenceReset";
+const char kTrackedSplitPrefHistogramChanged[] =
+    "Settings.TrackedSplitPreferenceChanged.";
+
+}  // namespace tracked_pref_histogram_names.