Componentize component_updater: Move some paths/constants to component.

components/component_updater/pref_names.h

Index: components/component_updater/pref_names.h
diff --git a/components/invalidation/invalidation_prefs.h b/components/component_updater/pref_names.h
similarity index 50%
copy from components/invalidation/invalidation_prefs.h
copy to components/component_updater/pref_names.h
index 2fdc5f230e504c02bb95b26474762285a36ed4a0..aedc2b1adc2e6b1f081b0a7d0e9656676b30a8ad 100644
--- a/components/invalidation/invalidation_prefs.h
+++ b/components/component_updater/pref_names.h
@@ -2,14 +2,13 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-namespace invalidation {
-namespace prefs {
-
-extern const char kInvalidatorClientId[];
+#ifndef COMPONENTS_COMPONENT_UPDATER_PREF_NAMES_H_
+#define COMPONENTS_COMPONENT_UPDATER_PREF_NAMES_H_
 
-extern const char kInvalidatorInvalidationState[];
+namespace prefs {
 
-extern const char kInvalidatorSavedInvalidations[];
+extern const char kRecoveryComponentVersion[];
 
 }  // namespace prefs
-}  // namespace invalidation
+
+#endif  // COMPONENTS_COMPONENT_UPDATER_PREF_NAMES_H_