Ensure OAuth2TokenServiceRequest::Core is destroyed on owner thread.

google_apis/gaia/oauth2_token_service_request.cc

Index: google_apis/gaia/oauth2_token_service_request.cc
diff --git a/google_apis/gaia/oauth2_token_service_request.cc b/google_apis/gaia/oauth2_token_service_request.cc
index c946fde088e89f31d7edbf1206bfe22adbbe1e4a..672015241779a45d4e8f1dea882947d0844c3011 100644
--- a/google_apis/gaia/oauth2_token_service_request.cc
+++ b/google_apis/gaia/oauth2_token_service_request.cc
@@ -71,6 +71,8 @@ class OAuth2TokenServiceRequest::Core
  private:
   friend class base::RefCountedThreadSafe<OAuth2TokenServiceRequest::Core>;
 
+  void DoNothing();
+
   scoped_refptr<base::SingleThreadTaskRunner> token_service_task_runner_;
   OAuth2TokenServiceRequest* owner_;
   TokenServiceProvider* provider_;
@@ -104,10 +106,16 @@ void OAuth2TokenServiceRequest::Core::Stop() {
   // Detaches |owner_| from this instance so |owner_| will be called back only
   // if |Stop()| has never been called.
   owner_ = NULL;
-  token_service_task_runner_->PostTask(
+
+  // We are stopping and will likely be destroyed soon.  Use a reply closure
+  // (DoNothing) to retain "this" and ensure we are destroyed in the owner
+  // thread, not the task runner thread.  PostTaskAndReply guarantees that the
+  // reply closure will execute after StopOnTokenServiceThread has completed.
+  token_service_task_runner_->PostTaskAndReply(
       FROM_HERE,
       base::Bind(&OAuth2TokenServiceRequest::Core::StopOnTokenServiceThread,
-                 this));
+                 this),
+      base::Bind(&OAuth2TokenServiceRequest::Core::DoNothing, this));
 }
 
 bool OAuth2TokenServiceRequest::Core::IsStopped() const {
@@ -130,6 +138,10 @@ OAuth2TokenServiceRequest* OAuth2TokenServiceRequest::Core::owner() {
   return owner_;
 }
 
+void OAuth2TokenServiceRequest::Core::DoNothing() {
+  DCHECK(CalledOnValidThread());
+}
+
 namespace {
 
 // An implementation of Core for getting an access token.