Remove implicit conversions from scoped_refptr to T* in chrome/browser/sync_file_system/

chrome/browser/sync_file_system/drive_backend/callback_helper.h

Index: chrome/browser/sync_file_system/drive_backend/callback_helper.h
diff --git a/chrome/browser/sync_file_system/drive_backend/callback_helper.h b/chrome/browser/sync_file_system/drive_backend/callback_helper.h
index ba01b67691f42f02e9ae2e893abbbc1067fbe0f6..bce337769c3a9aebef330879314c3434a5ccaed7 100644
--- a/chrome/browser/sync_file_system/drive_backend/callback_helper.h
+++ b/chrome/browser/sync_file_system/drive_backend/callback_helper.h
@@ -48,7 +48,7 @@ class CallbackHolder {
       : task_runner_(task_runner),
         from_here_(from_here),
         callback_(new base::Callback<T>(callback)) {
-    DCHECK(task_runner_);
+    DCHECK(task_runner_.get());
   }
 
   ~CallbackHolder() {
@@ -57,7 +57,7 @@ class CallbackHolder {
       delete callback;
   }
 
-  base::SequencedTaskRunner* task_runner() const { return task_runner_; }
+  base::SequencedTaskRunner* task_runner() const { return task_runner_.get(); }
   const tracked_objects::Location& from_here() const { return from_here_; }
   const base::Callback<T>& callback() const { return *callback_; }