[BlobStorage] Fix IPC race in sending IPC and posting to IO thread

content/child/blob_storage/blob_transport_controller_unittest.cc

 // Copyright 2015 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 "content/child/blob_storage/blob_transport_controller.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include "base/memory/ptr_util.h"
@@ skipping 263 matching lines @@
 
   BlobConsolidation* consolidation = new BlobConsolidation();
   consolidation->AddBlobItem(KRefBlobUUID, 10, 10);
   BlobTransportController::InitiateBlobTransfer(
       kBlobUUID, kBlobContentType, base::WrapUnique(consolidation), sender_,
       io_thread_runner_.get(), main_thread_runner_);
   // Check that we have the 'increase ref' pending task.
   EXPECT_TRUE(main_thread_runner_->HasPendingTask());
   // Check that we have the 'store' pending task.
   EXPECT_TRUE(io_thread_runner_->HasPendingTask());
+
+  io_thread_runner_->RunPendingTasks();
   // Check that we've sent the data.
   ExpectRegisterAndStartMessage(kBlobUUID, kBlobContentType,
                                 &message_descriptions);
   main_thread_runner_->ClearPendingTasks();
 
   // Check that we got the correct start message.
-  EXPECT_FALSE(holder->IsTransporting(kBlobUUID));
-  io_thread_runner_->RunPendingTasks();
   EXPECT_TRUE(holder->IsTransporting(kBlobUUID));
   base::Tuple<std::string, std::vector<DataElement>> message_contents;
   EXPECT_EQ(MakeBlobElement(KRefBlobUUID, 10, 10), message_descriptions[0]);
 
   holder->OnCancel(kBlobUUID,
                    storage::IPCBlobCreationCancelCode::OUT_OF_MEMORY);
   EXPECT_FALSE(holder->IsTransporting(kBlobUUID));
   // Check we have the 'decrease ref' task.
   EXPECT_TRUE(main_thread_runner_->HasPendingTask());
   main_thread_runner_->ClearPendingTasks();
@@ skipping 37 matching lines @@
   std::vector<storage::BlobItemBytesResponse> output;
 
   // Error conditions
   EXPECT_EQ(ResponsesStatus::BLOB_NOT_FOUND,
             holder->GetResponses(kBadBlobUUID, requests, &memory_handles,
                                  file_handles, &output));
   EXPECT_EQ(0u, output.size());
 }
 
 }  // namespace content