Fixed crash in WebFrameImpl::resetMatchCount function.

Source/web/tests/WebFrameTest.cpp

 /*
  * Copyright (C) 2010 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 3396 matching lines @@
 
     // The first scopeStringMatches will have reset the state. Detach before it actually scopes.
     EXPECT_TRUE(mainFrame->document().getElementById("frame").remove());
 
     runPendingTasks();
     EXPECT_TRUE(client.findResultsAreReady());
 
     holdSecondFrame.release();
 }
 
+TEST_F(WebFrameTest, ResetMatchCount)
+{
+    registerMockedHttpURLLoad("find_in_generated_frame.html");
+
+    FindUpdateWebFrameClient client;
+    FrameTestHelpers::WebViewHelper webViewHelper;
+    webViewHelper.initializeAndLoad(m_baseURL + "find_in_generated_frame.html", true, &client);
+    webViewHelper.webView()->resize(WebSize(640, 480));
+    webViewHelper.webView()->layout();
+    runPendingTasks();
+
+    static const char* kFindString = "result";
+    static const int kFindIdentifier = 12345;
+
+    WebFindOptions options;
+    WebString searchText = WebString::fromUTF8(kFindString);
+    WebLocalFrameImpl* mainFrame = toWebLocalFrameImpl(webViewHelper.webView()->mainFrame());
+
+    // Check that child frame exists.
+    EXPECT_TRUE(!!mainFrame->traverseNext(false));
+
+    for (WebFrame* frame = mainFrame; frame; frame = frame->traverseNext(false)) {
+        EXPECT_FALSE(frame->find(kFindIdentifier, searchText, options, false, 0));
+    }
+
+    runPendingTasks();
+    EXPECT_FALSE(client.findResultsAreReady());
+
+    mainFrame->resetMatchCount();
+}
+
 TEST_F(WebFrameTest, SetTickmarks)
 {
     registerMockedHttpURLLoad("find.html");
 
     FindUpdateWebFrameClient client;
     FrameTestHelpers::WebViewHelper webViewHelper;
     webViewHelper.initializeAndLoad(m_baseURL + "find.html", true, &client);
     webViewHelper.webView()->resize(WebSize(640, 480));
     webViewHelper.webView()->layout();
     runPendingTasks();
@@ skipping 2016 matching lines @@
     registerMockedHttpURLLoad("link-manifest-change.html");
 
     ManifestChangeWebFrameClient webFrameClient;
     FrameTestHelpers::WebViewHelper webViewHelper;
     webViewHelper.initializeAndLoad(m_baseURL + "link-manifest-change.html", true, &webFrameClient);
 
     EXPECT_EQ(14, webFrameClient.manifestChangeCount());
 }
 
 } // namespace