[SyncFS] Add UMAs to track syncfs usage

chrome/browser/sync_file_system/remote_file_sync_service.h

 // Copyright (c) 2012 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 CHROME_BROWSER_SYNC_FILE_SYSTEM_REMOTE_FILE_SYNC_SERVICE_H_
 #define CHROME_BROWSER_SYNC_FILE_SYSTEM_REMOTE_FILE_SYNC_SERVICE_H_
 
 #include <map>
 #include <set>
 #include <string>
@@ skipping 23 matching lines @@
 namespace sync_file_system {
 
 class FileStatusObserver;
 class LocalChangeProcessor;
 class RemoteChangeProcessor;
 
 enum RemoteServiceState {
   // Remote service is up and running, or has not seen any errors yet.
   // The consumer of this service can make new requests while the
   // service is in this state.
-  REMOTE_SERVICE_OK,
+  REMOTE_SERVICE_OK = 0,
 
   // Remote service is temporarily unavailable due to network,
   // authentication or some other temporary failure.
   // This state may be automatically resolved when the underlying
   // network condition or service condition changes.
   // The consumer of this service can still make new requests but
   // they may fail (with recoverable error code).
   REMOTE_SERVICE_TEMPORARY_UNAVAILABLE,
 
   // Remote service is temporarily unavailable due to authentication failure.
   // This state may be automatically resolved when the authentication token
   // has been refreshed internally (e.g. when the user signed in etc).
   // The consumer of this service can still make new requests but
   // they may fail (with recoverable error code).
   REMOTE_SERVICE_AUTHENTICATION_REQUIRED,
 
   // Remote service is disabled by configuration change or due to some
   // unrecoverable errors, e.g. local database corruption.
   // Any new requests will immediately fail when the service is in
   // this state.
   REMOTE_SERVICE_DISABLED,
+
+  REMOTE_SERVICE_STATE_MAX,
 };
 
 // This class represents a backing service of the sync filesystem.
 // This also maintains conflict information, i.e. a list of conflicting files
 // (at least in the current design).
 // Owned by SyncFileSystemService.
 class RemoteFileSyncService {
  public:
   enum BackendVersion {
     V1,
@@ skipping 157 matching lines @@
 
   virtual void PromoteDemotedChanges() = 0;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(RemoteFileSyncService);
 };
 
 }  // namespace sync_file_system
 
 #endif  // CHROME_BROWSER_SYNC_FILE_SYSTEM_REMOTE_FILE_SYNC_SERVICE_H_