Cleanup: Pass std::string as const reference from content/

content/browser/renderer_host/render_widget_host_view_browsertest.cc

 // Copyright (c) 2013 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 "base/barrier_closure.h"
 #include "base/command_line.h"
 #include "base/location.h"
 #include "base/path_service.h"
 #include "base/run_loop.h"
 #include "base/single_thread_task_runner.h"
@@ skipping 502 matching lines @@
     video_renderer.Copy(video_frame, &canvas, media::Context3D());
 
     ReadbackRequestCallbackTest(quit_callback, bitmap, READBACK_SUCCESS);
   }
 
   void SetAllowableError(int amount) { allowable_error_ = amount; }
   void SetExcludeRect(gfx::Rect exclude) { exclude_rect_ = exclude; }
 
   GURL TestUrl() override { return GURL(test_url_); }
 
-  void SetTestUrl(std::string url) { test_url_ = url; }
+  void SetTestUrl(const std::string& url) { test_url_ = url; }
 
   // Loads a page two boxes side-by-side, each half the width of
   // |html_rect_size|, and with different background colors. The test then
   // copies from |copy_rect| region of the page into a bitmap of size
   // |output_size|, and examines the resulting bitmap/VideoFrame.
   // Note that |output_size| may not have the same size as |copy_rect| (e.g.
   // when the output is scaled).
   void PerformTestWithLeftRightRects(const gfx::Size& html_rect_size,
                                      const gfx::Rect& copy_rect,
                                      const gfx::Size& output_size,
@@ skipping 421 matching lines @@
                         kTestCompositingModes);
 INSTANTIATE_TEST_CASE_P(
     GLAndSoftwareCompositing,
     CompositingRenderWidgetHostViewBrowserTestTabCaptureHighDPI,
     kTestCompositingModes);
 
 #endif  // !defined(OS_ANDROID) && !defined(OS_IOS)
 
 }  // namespace
 }  // namespace content