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

third_party/WebKit/Source/platform/scheduler/renderer/user_model_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 "platform/scheduler/renderer/user_model.h"
 
 #include "base/test/simple_test_tick_clock.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace blink {
 namespace scheduler {
 
-class UserModelTest : public testing::Test {
+class UserModelTest : public ::testing::Test {
  public:
   UserModelTest() {}
   ~UserModelTest() override {}
 
   void SetUp() override {
     clock_.reset(new base::SimpleTestTickClock());
     clock_->Advance(base::TimeDelta::FromMicroseconds(5000));
 
     user_model_.reset(new UserModel());
   }
@@ skipping 232 matching lines @@
       blink::WebInputEvent::Type::kGestureScrollBegin, clock_->NowTicks());
   EXPECT_EQ(priority_escalation_after_input_duration(),
             user_model_->TimeLeftInUserGesture(clock_->NowTicks()));
   user_model_->Reset(clock_->NowTicks());
   EXPECT_EQ(base::TimeDelta(),
             user_model_->TimeLeftInUserGesture(clock_->NowTicks()));
 }
 
 }  // namespace scheduler
 }  // namespace blink