Be explicit about namespace testing to not mix it with blink::testing

third_party/WebKit/Source/core/scheduler/ActiveConnectionThrottlingTest.cpp

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code if governed by a BSD-style license that can be
 // found in LICENSE file.
 
 #include "core/exported/WebViewBase.h"
 #include "core/frame/WebLocalFrameBase.h"
 #include "core/testing/sim/SimRequest.h"
 #include "core/testing/sim/SimTest.h"
 #include "platform/scheduler/renderer/web_view_scheduler.h"
 #include "platform/testing/TestingPlatformSupport.h"
 #include "platform/testing/TestingPlatformSupportWithWebRTC.h"
 #include "platform/wtf/PtrUtil.h"
 #include "public/web/WebScriptSource.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
-using testing::_;
+using ::testing::_;
 
 namespace blink {
 
 class ActiveConnectionThrottlingTest : public SimTest {};
 
 TEST_F(ActiveConnectionThrottlingTest, WebSocketStopsThrottling) {
   SimRequest main_resource("https://example.com/", "text/html");
 
   LoadURL("https://example.com/");
 
@@ skipping 26 matching lines @@
       "</script>)");
 
   EXPECT_TRUE(WebView().Scheduler()->HasActiveConnectionForTest());
 
   MainFrame().ExecuteScript(WebString("data_channel.close();"));
 
   EXPECT_FALSE(WebView().Scheduler()->HasActiveConnectionForTest());
 }
 
 }  // namespace blink