Refactor libplatform unit tests to use GTest/GMock.

test/cctest/test-libplatform-default-platform.cc

-// Copyright 2014 the V8 project 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 "src/v8.h"
-
-#include "src/libplatform/default-platform.h"
-#include "test/cctest/cctest.h"
-#include "test/cctest/test-libplatform.h"
-
-using namespace v8::internal;
-using namespace v8::platform;
-
-
-TEST(DefaultPlatformMessagePump) {
-  TaskCounter task_counter;
-
-  DefaultPlatform platform;
-
-  TestTask* task = new TestTask(&task_counter, true);
-
-  CHECK(!platform.PumpMessageLoop(CcTest::isolate()));
-
-  platform.CallOnForegroundThread(CcTest::isolate(), task);
-
-  CHECK_EQ(1, task_counter.GetCount());
-  CHECK(platform.PumpMessageLoop(CcTest::isolate()));
-  CHECK_EQ(0, task_counter.GetCount());
-  CHECK(!platform.PumpMessageLoop(CcTest::isolate()));
-}