sync: add a SyncSessionJobPurpose for clearing sync user data.

chrome/browser/sync/engine/syncer.h

 // Copyright (c) 2010 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_ENGINE_SYNCER_H_
 #define CHROME_BROWSER_SYNC_ENGINE_SYNCER_H_
 #pragma once
 
 #include <utility>
 #include <vector>
@@ skipping 38 matching lines @@
   VERIFY_UPDATES,
   PROCESS_UPDATES,
   STORE_TIMESTAMPS,
   APPLY_UPDATES,
   BUILD_COMMIT_REQUEST,
   POST_COMMIT_MESSAGE,
   PROCESS_COMMIT_RESPONSE,
   BUILD_AND_PROCESS_CONFLICT_SETS,
   RESOLVE_CONFLICTS,
   APPLY_UPDATES_TO_RESOLVE_CONFLICTS,
-  CLEAR_PRIVATE_DATA,
+  CLEAR_PRIVATE_DATA,  // TODO(tim): Rename 'private' to 'user'.
   SYNCER_END
 };
 
 // A Syncer provides a control interface for driving the individual steps
 // of the sync cycle.  Each cycle (hopefully) moves the client into closer
 // synchronization with the server.  The individual steps are modeled
 // as SyncerCommands, and the ordering of the steps is expressed using
 // the SyncerStep enum.
 //
 // A Syncer instance expects to run on a dedicated thread.  Calls
 // to SyncShare() may take an unbounded amount of time, as SyncerCommands
 // may block on network i/o, on lock contention, or on tasks posted to
 // other threads.
 class Syncer {
  public:
   typedef std::vector<int64> UnsyncedMetaHandles;
 
   // The constructor may be called from a thread that is not the Syncer's
   // dedicated thread, to allow some flexibility in the setup.
   Syncer();
   virtual ~Syncer();
 
   // Called by other threads to tell the syncer to stop what it's doing
   // and return early from SyncShare, if possible.
   bool ExitRequested();
   void RequestEarlyExit();
 
+  // TODO(tim): Deprecated.
   // Cause one sync cycle to occur.  Like a good parent, it is the caller's
   // responsibility to clean up after the syncer when it finishes a sync share
   // operation and honor server mandated throttles.
   virtual void SyncShare(sessions::SyncSession* session);
 
+  // Like SyncShare() above, but |first_step| and |last_step| are provided to
+  // perform a partial sync cycle, stopping after |last_step| is performed.
+  virtual void SyncShare(sessions::SyncSession* session,
+                         SyncerStep first_step,
+                         SyncerStep last_step);
+
  private:
   // Implements the PROCESS_CLIENT_COMMAND syncer step.
   void ProcessClientCommand(sessions::SyncSession *session);
 
-  // This is the bottom-most SyncShare variant, and does not cause transient
-  // state to be reset in session.
-  // Like SyncShare(), but |first_step| and |last_step| are provided to perform
-  // a partial sync cycle, stopping after |last_step| is performed.
-  void SyncShare(sessions::SyncSession* session,
-                 SyncerStep first_step,
-                 SyncerStep last_step);
-
   bool early_exit_requested_;
   base::Lock early_exit_requested_lock_;
 
   ConflictResolver resolver_;
 
   // A callback hook used in unittests to simulate changes between conflict set
   // building and conflict resolution.
   Callback0::Type* pre_conflict_resolution_closure_;
 
   friend class SyncerTest;
@@ skipping 45 matching lines @@
   return false;
 }
 // Utility function declarations.
 void CopyServerFields(syncable::Entry* src, syncable::MutableEntry* dest);
 void ClearServerData(syncable::MutableEntry* entry);
 
 }  // namespace browser_sync
 
 #endif  // CHROME_BROWSER_SYNC_ENGINE_SYNCER_H_