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

third_party/WebKit/Source/core/html/HTMLIFrameElementAllowTest.cpp

 // Copyright 2017 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 "core/html/HTMLIFrameElementAllow.h"
 
 #include "core/dom/Document.h"
 #include "core/html/HTMLIFrameElement.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
-using testing::UnorderedElementsAre;
+using ::testing::UnorderedElementsAre;
 
 namespace blink {
 
 TEST(HTMLIFrameElementAllowTest, ParseAllowedFeatureNamesValid) {
   Document* document = Document::Create();
   HTMLIFrameElement* iframe = HTMLIFrameElement::Create(*document);
   HTMLIFrameElementAllow* allow =
       static_cast<HTMLIFrameElementAllow*>(iframe->allow());
   String error_message;
   Vector<WebFeaturePolicyFeature> result;
@@ skipping 33 matching lines @@
   EXPECT_EQ("'invalid1', 'invalid2' are invalid feature names.", error_message);
 
   allow->setValue("fullscreen invalid payment fullscreen");
   result = allow->ParseAllowedFeatureNames(error_message);
   EXPECT_EQ("'invalid' is an invalid feature name.", error_message);
   EXPECT_THAT(result, UnorderedElementsAre(WebFeaturePolicyFeature::kFullscreen,
                                            WebFeaturePolicyFeature::kPayment));
 }
 
 }  // namespace blink