[Sync] change BridgeTask from Callback to OnceCallback.

change ModelTypeController::BridgeTask from Callback to OnceCallback.

Bug: 786478
Change-Id: I5d559aafefa3917b5cde5e06f398078989b3bc10
Reviewed-on: https://chromium-review.googlesource.com/777386
Commit-Queue: Gang Wu <gangwu@chromium.org>
Reviewed-by: Sky Malice <skym@chromium.org>
Cr-Commit-Position: refs/heads/master@{#517633}

components/history/core/browser/typed_url_model_type_controller.cc

@@ -25,8 +25,8 @@ namespace {
 // the tasks we want to run.
 class RunTaskOnHistoryThread : public HistoryDBTask {
  public:
-  explicit RunTaskOnHistoryThread(const ModelTypeController::BridgeTask& task)
-      : task_(task) {}
+  explicit RunTaskOnHistoryThread(ModelTypeController::BridgeTask task)
+      : task_(std::move(task)) {}
 
   bool RunOnDBThread(HistoryBackend* backend, HistoryDatabase* db) override {
     // Invoke the task, then free it immediately so we don't keep a reference
@@ -34,13 +34,9 @@ class RunTaskOnHistoryThread : public HistoryDBTask {
     // main thread - we want to release references as soon as possible to avoid
     // keeping them around too long during shutdown.
     TypedURLSyncBridge* bridge = backend->GetTypedURLSyncBridge();
-    if (!bridge) {
-      NOTREACHED();
-      return true;
-    }
+    DCHECK(bridge);
 
-    task_.Run(bridge);
-    task_.Reset();
+    std::move(task_).Run(bridge);
     return true;
   }
 
@@ -73,7 +69,7 @@ bool TypedURLModelTypeController::ReadyForStart() const {
 }
 
 void TypedURLModelTypeController::PostBridgeTask(const base::Location& location,
-                                                 const BridgeTask& task) {
+                                                 BridgeTask task) {
   history::HistoryService* history = sync_client()->GetHistoryService();
   if (!history) {
     // History must be disabled - don't start.
@@ -81,8 +77,9 @@ void TypedURLModelTypeController::PostBridgeTask(const base::Location& location,
     return;
   }
 
-  history->ScheduleDBTask(std::make_unique<RunTaskOnHistoryThread>(task),
-                          &task_tracker_);
+  history->ScheduleDBTask(
+      std::make_unique<RunTaskOnHistoryThread>(std::move(task)),
+      &task_tracker_);
 }
 
 void TypedURLModelTypeController::OnSavingBrowserHistoryDisabledChanged() {

components/history/core/browser/typed_url_model_type_controller.h

@@ -23,8 +23,7 @@ class TypedURLModelTypeController : public syncer::ModelTypeController {
 
  private:
   // syncer::ModelTypeController implementation.
-  void PostBridgeTask(const base::Location& location,
-                      const BridgeTask& task) override;
+  void PostBridgeTask(const base::Location& location, BridgeTask task) override;
 
   void OnSavingBrowserHistoryDisabledChanged();
 

components/sync/driver/model_type_controller.cc

@@ -52,11 +52,10 @@ base::WeakPtr<ModelTypeSyncBridge> ReturnCapturedBridge(
   return arg;
 }
 
-void RunBridgeTask(const BridgeProvider& bridge_provider,
-                   const BridgeTask& task) {
-  if (base::WeakPtr<ModelTypeSyncBridge> bridge = bridge_provider.Run()) {
-    task.Run(bridge.get());
-  }
+void RunBridgeTask(BridgeProvider bridge_provider, BridgeTask task) {
+  base::WeakPtr<ModelTypeSyncBridge> bridge = std::move(bridge_provider).Run();
+  if (bridge.get())
+    std::move(task).Run(bridge.get());
 }
 
 }  // namespace
@@ -263,10 +262,11 @@ BridgeProvider ModelTypeController::GetBridgeProvider() {
 }
 
 void ModelTypeController::PostBridgeTask(const base::Location& location,
-                                         const BridgeTask& task) {
+                                         BridgeTask task) {
   DCHECK(model_thread_);
   model_thread_->PostTask(
-      location, base::Bind(&RunBridgeTask, GetBridgeProvider(), task));
+      location, base::Bind(&RunBridgeTask, base::Passed(GetBridgeProvider()),
+                           base::Passed(std::move(task))));
 }
 
 }  // namespace syncer

components/sync/driver/model_type_controller.h

@@ -27,8 +27,9 @@ struct ActivationContext;
 // DataTypeController implementation for Unified Sync and Storage model types.
 class ModelTypeController : public DataTypeController {
  public:
-  using BridgeProvider = base::Callback<base::WeakPtr<ModelTypeSyncBridge>()>;
-  using BridgeTask = base::Callback<void(ModelTypeSyncBridge*)>;
+  using BridgeProvider =
+      base::OnceCallback<base::WeakPtr<ModelTypeSyncBridge>()>;
+  using BridgeTask = base::OnceCallback<void(ModelTypeSyncBridge*)>;
 
   ModelTypeController(
       ModelType type,
@@ -76,8 +77,7 @@ class ModelTypeController : public DataTypeController {
 
   // Post the given task that requires the bridge object to run to the model
   // thread, where the bridge lives.
-  virtual void PostBridgeTask(const base::Location& location,
-                              const BridgeTask& task);
+  virtual void PostBridgeTask(const base::Location& location, BridgeTask task);
 
   // The sync client, which provides access to this type's ModelTypeSyncBridge.
   SyncClient* const sync_client_;