Move plugin_browsertests.cc from browser_tests to content_browsertests.

content/test/content_browser_test.h

 // Copyright (c) 2012 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 CONTENT_TEST_CONTENT_BROWSER_TEST_H_
 #define CONTENT_TEST_CONTENT_BROWSER_TEST_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "content/public/test/browser_test.h"
 #include "content/test/browser_test_base.h"
 
-
 namespace content {
 class Shell;
 class ShellMainDelegate;
 
 class ContentBrowserTest : public BrowserTestBase {
  protected:
   ContentBrowserTest();
   virtual ~ContentBrowserTest();
 
   // testing::Test:
   virtual void SetUp() OVERRIDE;
   virtual void TearDown() OVERRIDE;
 
   // BrowserTestBase:
   virtual void RunTestOnMainThreadLoop() OVERRIDE;
 
+ protected:
   // Returns the window for the test.
   Shell* shell() const { return shell_; }
 
  private:
    scoped_ptr<content::ShellMainDelegate> shell_main_delegate_;
 
   Shell* shell_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_TEST_CONTENT_BROWSER_TEST_H_