[Sync] Refactor sync configuration logic.

chrome/browser/sync/glue/sync_backend_host.h

Index: chrome/browser/sync/glue/sync_backend_host.h
diff --git a/chrome/browser/sync/glue/sync_backend_host.h b/chrome/browser/sync/glue/sync_backend_host.h
index e8785540b6a47ef3a10edc16b1fb3ac89138d725..08e69894c0d9cc343ca3082e626c8f7437e3e33c 100644
--- a/chrome/browser/sync/glue/sync_backend_host.h
+++ b/chrome/browser/sync/glue/sync_backend_host.h
@@ -225,16 +225,12 @@ class SyncBackendHost : public BackendDataTypeConfigurer {
   // set of all types that failed configuration (i.e., if its argument
   // is non-empty, then an error was encountered).
   virtual void ConfigureDataTypes(
-      sync_api::ConfigureReason reason,
-      syncable::ModelTypeSet types_to_add,
-      syncable::ModelTypeSet types_to_remove,
+      const sync_api::ConfigureReason& reason,
+      const syncable::ModelTypeSet& desired_types,
+      const syncable::ModelTypeSet& disabled_types,
       NigoriState nigori_state,
-      base::Callback<void(syncable::ModelTypeSet)> ready_task,
-      base::Callback<void()> retry_callback) OVERRIDE;
-
-  // Makes an asynchronous call to syncer to switch to config mode. When done
-  // syncer will call us back on FinishConfigureDataTypes.
-  virtual void StartConfiguration(const base::Closure& callback);
+      const base::Callback<void(syncable::ModelTypeSet)>& ready_task,
+      const base::Callback<void()>& retry_callback) OVERRIDE;
 
   // Turns on encryption of all present and future sync data.
   virtual void EnableEncryptEverything();
@@ -338,9 +334,26 @@ class SyncBackendHost : public BackendDataTypeConfigurer {
   void HandleSyncCycleCompletedOnFrontendLoop(
       const sessions::SyncSessionSnapshot& snapshot);
 
-  // Called to finish the job of ConfigureDataTypes once the syncer is in
-  // configuration mode.
-  void FinishConfigureDataTypesOnFrontendLoop();
+  // Request the syncer to reconfigure with the specfied params.
+  // Virtual for testing.
+  virtual void RequestConfigureSyncer(
+      sync_api::ConfigureReason reason,
+      syncable::ModelTypeSet types_to_config,
+      const browser_sync::ModelSafeRoutingInfo routing_info,
+      const base::Callback<void(syncable::ModelTypeSet)>& ready_task,
+      const base::Closure& retry_callback);
+
+  // Called when the syncer has finished performing a configuration.
+  void FinishConfigureDataTypesOnFrontendLoop(
+      const syncable::ModelTypeSet& types_to_configure,
+      const syncable::ModelTypeSet& configured_types,
+      const base::Callback<void(syncable::ModelTypeSet)>& ready_task);
+
+  // Called when the syncer failed to perform a configuration and will
+  // eventually retry. FinishingConfigurationOnFrontendLoop(..) will be called
+  // on successful completion.
+  void RetryConfigurationOnFrontendLoop(
+      const base::Closure& retry_callback);
 
   bool IsDownloadingNigoriForTest() const;
 
@@ -365,32 +378,6 @@ class SyncBackendHost : public BackendDataTypeConfigurer {
     INITIALIZED,            // Initialization is complete.
   };
 
-  struct PendingConfigureDataTypesState {
-    PendingConfigureDataTypesState();
-    ~PendingConfigureDataTypesState();
-
-    // The ready_task will be run when configuration is done with the
-    // set of all types that failed configuration (i.e., if its
-    // argument is non-empty, then an error was encountered).
-    base::Callback<void(syncable::ModelTypeSet)> ready_task;
-
-    // The retry callback will be run when the download failed due to a
-    // transient error. This is to notify DTM so it can apropriately inform
-    // the UI. Note: The retry_callback will be run only once and after
-    // that we will not notify DTM until the sync is successful or in a
-    // permanent error state.
-    base::Callback<void()> retry_callback;
-
-    // The set of types that we are waiting to be initially synced in a
-    // configuration cycle.
-    syncable::ModelTypeSet types_to_add;
-
-    // Additional details about which types were added.
-    syncable::ModelTypeSet added_types;
-    sync_api::ConfigureReason reason;
-    bool retry_in_progress;
-  };
-
   // Checks if we have received a notice to turn on experimental datatypes
   // (via the nigori node) and informs the frontend if that is the case.
   // Note: it is illegal to call this before the backend is initialized.
@@ -509,9 +496,6 @@ class SyncBackendHost : public BackendDataTypeConfigurer {
   // The frontend which we serve (and are owned by).
   SyncFrontend* frontend_;
 
-  scoped_ptr<PendingConfigureDataTypesState> pending_download_state_;
-  scoped_ptr<PendingConfigureDataTypesState> pending_config_mode_state_;
-
   // We cache the cryptographer's pending keys whenever NotifyPassphraseRequired
   // is called. This way, before the UI calls SetDecryptionPassphrase on the
   // syncer, it can avoid the overhead of an asynchronous decryption call and