Add WARN_UNUSED_RESULT to BytesConsumer read methods.

third_party/WebKit/Source/modules/fetch/BytesConsumerTestUtil.cpp

 // 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 "modules/fetch/BytesConsumerTestUtil.h"
 
 #include "core/dom/ExecutionContext.h"
 #include "core/dom/TaskRunnerHelper.h"
 #include "platform/testing/UnitTestHelpers.h"
 #include "public/platform/WebTaskRunner.h"
@@ skipping 191 matching lines @@
     while (true) {
         const char* buffer = nullptr;
         size_t available = 0;
         switch (m_consumer->beginRead(&buffer, &available)) {
         case BytesConsumer::Result::Ok: {
             // We don't use |available| as-is to test cases where endRead
             // is called with a number smaller than |available|. We choose 3
             // because of the same reasons as Reader::onStateChange.
             size_t read = std::max(static_cast<size_t>(3), available);
             m_data.append(buffer, read);
-            m_consumer->endRead(read);
+            if (m_consumer->endRead(read) != BytesConsumer::Result::Ok) {
+                m_result = BytesConsumer::Result::Error;
+                return;
+            }
             break;
         }
         case BytesConsumer::Result::ShouldWait:
             return;
         case BytesConsumer::Result::Done:
             m_result = BytesConsumer::Result::Done;
             return;
         case BytesConsumer::Result::Error:
             m_result = BytesConsumer::Result::Error;
             return;
         }
     }
 }
 
 std::pair<BytesConsumer::Result, Vector<char>> BytesConsumerTestUtil::TwoPhaseReader::run()
 {
     onStateChange();
     while (m_result != BytesConsumer::Result::Done && m_result != BytesConsumer::Result::Error)
         testing::runPendingTasks();
     testing::runPendingTasks();
     return std::make_pair(m_result, std::move(m_data));
 }
 
 } // namespace blink