Putting histogram names of tracked prefs in tracked_preference_histogram_name file.

components/user_prefs/tracked/tracked_preference_histogram_names.h

Index: components/user_prefs/tracked/tracked_preference_histogram_names.h
diff --git a/components/user_prefs/tracked/tracked_preference_histogram_names.h b/components/user_prefs/tracked/tracked_preference_histogram_names.h
new file mode 100644
index 0000000000000000000000000000000000000000..cb1f1f0d7f81bf53a50353e7d4a6deede119752f
--- /dev/null
+++ b/components/user_prefs/tracked/tracked_preference_histogram_names.h
@@ -0,0 +1,25 @@
+// 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 COMPONENTS_USER_PREFS_TRACKED_TRACKED_PREFERENCE_HISTOGRAM_NAMES_H_
+#define COMPONENTS_USER_PREFS_TRACKED_TRACKED_PREFERENCE_HISTOGRAM_NAMES_H_
+
+namespace user_prefs {
+namespace tracked {
+
+extern const char kTrackedPrefHistogramUnchanged[];
+extern const char kTrackedPrefHistogramCleared[];
+extern const char kTrackedPrefHistogramMigratedLegacyDeviceId[];
+extern const char kTrackedPrefHistogramChanged[];
+extern const char kTrackedPrefHistogramInitialized[];
+extern const char kTrackedPrefHistogramTrustedInitialized[];
+extern const char kTrackedPrefHistogramNullInitialized[];
+extern const char kTrackedPrefHistogramWantedReset[];
+extern const char kTrackedPrefHistogramReset[];
+extern const char kTrackedSplitPrefHistogramChanged[];
+
+}  // namespace tracked.

[Bernhard Bauer, 2015/12/15 11:19:55]

No period at the end. Essentially, the comment should exactly mirror the
statement the opened the namespace.

[Deepak, 2015/12/15 11:28:28]

Done. Sorry I missed that.

+}  // namespace user_prefs.
+
+#endif  // COMPONENTS_USER_PREFS_TRACKED_TRACKED_PREFERENCE_HISTOGRAM_NAMES_H_