Fix crash in WebViewImpl::contentsPreferredMinimumSize

Source/web/tests/WebViewTest.cpp

 /*
  * Copyright (C) 2011, 2012 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 2604 matching lines @@
     url = m_baseURL + "specify_size.html?1.5px:1.5px";
     URLTestHelpers::registerMockedURLLoad(toKURL(url), "specify_size.html");
     webView = m_webViewHelper.initializeAndLoad(url, true);
 
     webView->setZoomLevel(WebView::zoomFactorToZoomLevel(1));
     size = webView->contentsPreferredMinimumSize();
     EXPECT_EQ(2, size.width);
     EXPECT_EQ(2, size.height);
 }
 
+TEST_F(WebViewTest, PreferredSizeDirtyLayout)
+{
+    std::string url = m_baseURL + "specify_size.html?100px:100px";
+    URLTestHelpers::registerMockedURLLoad(toKURL(url), "specify_size.html");
+    WebView* webView = m_webViewHelper.initializeAndLoad(url, true);
+    WebElement documentElement = webView->mainFrame()->document().documentElement();
+
+    WebSize size = webView->contentsPreferredMinimumSize();
+    EXPECT_EQ(100, size.width);
+    EXPECT_EQ(100, size.height);
+
+    bool setStyle = documentElement.setAttribute("style", "display: none");
+    EXPECT_TRUE(setStyle);
+
+    size = webView->contentsPreferredMinimumSize();
+    EXPECT_EQ(0, size.width);
+    EXPECT_EQ(0, size.height);
+}
+
 class UnhandledTapWebViewClient : public FrameTestHelpers::TestWebViewClient {
 public:
     void showUnhandledTapUIIfNeeded(const WebPoint& tappedPosition, const WebNode& tappedNode, bool pageChanged) override
     {
         m_wasCalled = true;
         m_tappedPosition = tappedPosition;
         m_tappedNode = tappedNode;
         m_pageChanged = pageChanged;
     }
     bool getWasCalled() const { return m_wasCalled; }
@@ skipping 705 matching lines @@
         webViewImpl->advanceFocusInForm(WebFocusTypeBackward);
     }
     // Now focus will stay on previous focus itself, because it has no previous
     // element.
     EXPECT_EQ(currentFocus, document->focusedElement());
 
     m_webViewHelper.reset();
 }
 
 } // namespace blink