Fix the DCHECK failure when starting and stopping GCMClient immediately

google_apis/gcm/engine/gcm_store_impl.cc

 // Copyright 2014 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.
 
 #include "google_apis/gcm/engine/gcm_store_impl.h"
 
 #include "base/basictypes.h"
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/file_util.h"
@@ skipping 709 matching lines @@
   blocking_task_runner_->PostTask(
       FROM_HERE,
       base::Bind(&GCMStoreImpl::Backend::Load,
                  backend_,
                  base::Bind(&GCMStoreImpl::LoadContinuation,
                             weak_ptr_factory_.GetWeakPtr(),
                             callback)));
 }
 
 void GCMStoreImpl::Close() {
+  weak_ptr_factory_.InvalidateWeakPtrs();
+  app_message_counts_.clear();
   blocking_task_runner_->PostTask(
       FROM_HERE,
       base::Bind(&GCMStoreImpl::Backend::Close, backend_));
 }
 
 void GCMStoreImpl::Destroy(const UpdateCallback& callback) {
   blocking_task_runner_->PostTask(
       FROM_HERE,
       base::Bind(&GCMStoreImpl::Backend::Destroy, backend_, callback));
 }
@@ skipping 205 matching lines @@
            removed_message_counts.begin();
        iter != removed_message_counts.end(); ++iter) {
     DCHECK_NE(app_message_counts_.count(iter->first), 0U);
     app_message_counts_[iter->first] -= iter->second;
     DCHECK_GE(app_message_counts_[iter->first], 0);
   }
   callback.Run(true);
 }
 
 }  // namespace gcm