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..cfbd77aeb4a483d9159bd131ab85007597bc3a46
--- /dev/null
+++ b/components/user_prefs/tracked/tracked_preference_histogram_names.h
@@ -0,0 +1,23 @@
+// 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_TRACKED_PREFERENCE_HISTOGRAM_NAMES_H_
+#define COMPONENTS_TRACKED_PREFERENCE_HISTOGRAM_NAMES_H_
+
+namespace tracked_pref_histogram_names {

[Bernhard Bauer, 2015/12/14 09:52:16]

I think the best namespace for this would be user_prefs, or user_prefs::tracked.
Either of those is going to be shorter (tracked_pref_histogram_names is very
unwieldy in the files above), they adhere to the namespace naming convention for
components, and inside of that namespace it's probably fine to use these symbols
directly, i.e. not have a namespace just for this file.

[Deepak, 2015/12/14 10:16:18]

I agree, tracked_pref_histogram_names namespace is too big.
I have made this like:
user_prefs::tracked
and keeping the names same.

+
+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_pref_histogram_names
+
+#endif  // COMPONENTS_TRACKED_PREFERENCE_HISTOGRAM_NAMES_H_