Adds test coverage for 521663

Source/web/tests/WebFrameTest.cpp

Index: Source/web/tests/WebFrameTest.cpp
diff --git a/Source/web/tests/WebFrameTest.cpp b/Source/web/tests/WebFrameTest.cpp
index 4a3f112917626400b361734eda6193e2b88165a5..de6a02718ed84ceb70f1f69e1c535dde4c9aa2cc 100644
--- a/Source/web/tests/WebFrameTest.cpp
+++ b/Source/web/tests/WebFrameTest.cpp
@@ -7022,6 +7022,38 @@ TEST_F(WebFrameSwapTest, SwapMainFrame)
     remoteFrame->close();
 }
 
+namespace {
+
+class SwapMainFrameWhenTitleChangesWebFrameClient : public FrameTestHelpers::TestWebFrameClient {
+public:
+    SwapMainFrameWhenTitleChangesWebFrameClient() {}
+    ~SwapMainFrameWhenTitleChangesWebFrameClient() override {}
+
+    void didReceiveTitle(WebLocalFrame* frame, const WebString& title, WebTextDirection direction) override

[Nate Chapin, 2015/09/04 18:30:47]

Style nit: drop the unused variable names.

[sky, 2015/09/04 18:57:13]

Done.

+    {
+        if (!frame->parent())
+            frame->swap(WebRemoteFrame::create(WebTreeScopeType::Document, nullptr));
+    }
+
+private:

[Nate Chapin, 2015/09/04 18:30:47]

Nit: remove this

[sky, 2015/09/04 18:57:13]

Done.

+};
+
+} // anonymous namespace
+
+TEST_F(WebFrameTest, SwapMainFrameWhileLoading)
+{
+    SwapMainFrameWhenTitleChangesWebFrameClient frameClient;
+
+    FrameTestHelpers::WebViewHelper webViewHelper;
+    registerMockedHttpURLLoad("frame-a-b-c.html");
+    registerMockedHttpURLLoad("subframe-a.html");
+    registerMockedHttpURLLoad("subframe-b.html");
+    registerMockedHttpURLLoad("subframe-c.html");
+    registerMockedHttpURLLoad("subframe-hello.html");
+
+    webViewHelper.initializeAndLoad(m_baseURL + "frame-a-b-c.html", true, &frameClient);
+}
+
 void swapAndVerifyFirstChildConsistency(const char* const message, WebFrame* parent, WebFrame* newChild)
 {
     SCOPED_TRACE(message);