Put Top Control resizing change behind a flag.

third_party/WebKit/Source/web/tests/TopControlsTest.cpp

 /*
  * Copyright (C) 2015 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 54 matching lines @@
         registerMockedHttpURLLoad("vh-height-width-800-extra-wide.html");
     }
 
     ~TopControlsTest() override
     {
         Platform::current()->unitTestSupport()->unregisterAllMockedURLs();
     }
 
     WebViewImpl* initialize(const std::string& pageName = "large-div.html")
     {
+        RuntimeEnabledFeatures::setInertTopControlsEnabled(true);
+
         // Load a page with large body and set viewport size to 400x400 to ensure
         // main frame is scrollable.
         m_helper.initializeAndLoad(m_baseURL + pageName, true, 0, 0, &configureSettings);
 
         webViewImpl()->resize(IntSize(400, 400));
         return webViewImpl();
     }
 
     static void configureSettings(WebSettings* settings)
     {
@@ skipping 638 matching lines @@
     // that's 1600px wide so the minimum scale is 0.25 to encompass that.
     ASSERT_EQ(0.25f, webView->minimumPageScaleFactor());
 
     // The viewport will match the layout width at scale=0.5 so the height used
     // for vh should be (300 / 0.5) for the layout height + (100 / 0.5) for top
     // controls = 800.
     EXPECT_EQ(800, frame()->view()->viewportSizeForViewportUnits().height());
 }
 
 } // namespace blink