Remove duplication between TestRunner's fields and LayoutDumpFlags struct.

components/test_runner/web_test_runner.h

 // Copyright 2014 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.
 
 #ifndef COMPONENTS_TEST_RUNNER_WEB_TEST_RUNNER_H_
 #define COMPONENTS_TEST_RUNNER_WEB_TEST_RUNNER_H_
 
 #include <string>
 #include <vector>
 
-#include "components/test_runner/layout_dump_flags.h"
+namespace test_runner {
+struct LayoutDumpFlags;
+}
 
 namespace blink {
 class WebContentSettingsClient;
 }
 
 namespace test_runner {
 
 class WebTestRunner {
  public:
   // Returns a mock WebContentSettings that is used for layout tests. An
   // embedder should use this for all WebViews it creates.
   virtual blink::WebContentSettingsClient* GetWebContentSettings() const = 0;
 
   // After WebTestDelegate::TestFinished was invoked, the following methods
   // can be used to determine what kind of dump the main WebTestProxy can
   // provide.
 
   // If true, WebTestDelegate::audioData returns an audio dump and no text
   // or pixel results are available.
   virtual bool ShouldDumpAsAudio() const = 0;
   virtual void GetAudioData(std::vector<unsigned char>* buffer_view) const = 0;
 
   // Gets layout dump flags (i.e. dump-as-text or dump-as-markup) requested
   // by the test (i.e. via testRunner.dumpAsText() called from javascript).
-  virtual LayoutDumpFlags GetLayoutDumpFlags() = 0;
+  virtual const LayoutDumpFlags& GetLayoutDumpFlags() = 0;
 
   // If custom text dump is present (i.e. if testRunner.setCustomTextOutput has
   // been called from javascript), then returns |true| and populates the
   // |custom_text_dump| argument.  Otherwise returns |false|.
   virtual bool HasCustomTextDump(std::string* custom_text_dump) const = 0;
 
   // Returns true if the call to WebTestProxy::captureTree will invoke
   // WebTestDelegate::captureHistoryForWindow.
   virtual bool ShouldDumpBackForwardList() const = 0;
 
   // Returns true if WebTestProxy::capturePixels should be invoked after
   // capturing text results.
   virtual bool ShouldGeneratePixelResults() = 0;
 
   virtual bool ShouldStayOnPageAfterHandlingBeforeUnload() const = 0;
 };
 
 }  // namespace test_runner
 
 #endif  // COMPONENTS_TEST_RUNNER_WEB_TEST_RUNNER_H_