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..30f3668f7a5752e9ec62dca24fc04099afd148c6 100644
--- a/Source/web/tests/WebFrameTest.cpp
+++ b/Source/web/tests/WebFrameTest.cpp
@@ -7022,6 +7022,80 @@ TEST_F(WebFrameSwapTest, SwapMainFrame)
     remoteFrame->close();
 }
 
+namespace {
+
+class ServeAsyncRequestsTask : public WebThread::Task {
+public:
+    ServeAsyncRequestsTask(FrameTestHelpers::TestWebFrameClient* client, bool* gotCommit)
+        : m_client(client)
+        , m_gotCommit(gotCommit)
+    {
+    }
+
+    void run() override
+    {
+        Platform::current()->unitTestSupport()->serveAsynchronousMockedRequests();

[sky, 2015/09/02 23:33:15]

This triggers a presubmit hook that fails. I had to use bypass-hooks to upload.
What should I be using?

+        if (!m_gotCommit)
+            Platform::current()->currentThread()->postTask(FROM_HERE, new ServeAsyncRequestsTask(m_client, m_gotCommit));
+        else
+            Platform::current()->unitTestSupport()->exitRunLoop();
+    }
+
+private:
+    FrameTestHelpers::TestWebFrameClient* const m_client;
+    bool* m_gotCommit;
+};
+
+// Starts a load for frame. The call returns once gotCommit is set to true.
+void StartLoad(WebFrame* frame, const std::string& url, FrameTestHelpers::TestWebFrameClient* client, bool* gotCommit)
+{
+    WebURLRequest urlRequest;
+    urlRequest.initialize();
+    urlRequest.setURL(URLTestHelpers::toKURL(url));
+
+    // Schedule a task to start the load, followed by a task that exits the run loop once gotCommit is set to true.
+    Platform::current()->currentThread()->postTask(FROM_HERE, new FrameTestHelpers::LoadTask(frame, urlRequest));
+    Platform::current()->currentThread()->postTask(FROM_HERE, new ServeAsyncRequestsTask(client, gotCommit));
+    Platform::current()->unitTestSupport()->enterRunLoop();
+}
+
+class SwapMainFrameWhileLoadingWebFrameClient : public FrameTestHelpers::TestWebFrameClient {
+public:
+    SwapMainFrameWhileLoadingWebFrameClient(bool* gotCommit) : m_gotCommit(gotCommit) {}
+    ~SwapMainFrameWhileLoadingWebFrameClient() override {}
+
+    void didCommitProvisionalLoad(WebLocalFrame*, const WebHistoryItem&, WebHistoryCommitType) override
+    {
+        *m_gotCommit = true;
+    }
+
+private:
+    bool* m_gotCommit;
+};
+
+} // anonymous namespace
+
+TEST_F(WebFrameTest, SwapMainFrameWhileLoading)
+{
+    bool gotCommit = false;
+    SwapMainFrameWhileLoadingWebFrameClient frameClient(&gotCommit);
+
+    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.initialize(true, &frameClient);
+
+    WebFrame* mainFrame = webViewHelper.webView()->mainFrame();
+    StartLoad(mainFrame, m_baseURL + "frame-a-b-c.html", &frameClient, &gotCommit);

[Nate Chapin, 2015/09/03 21:02:06]

What does this (and above) do that webViewHelper.initializeAndLoad() doesn't?

[sky, 2015/09/03 21:03:44]

It pumps events until didCommitProvisionalLoad is received, then it stops.

[Nate Chapin, 2015/09/03 21:52:38]

Instead of pumping manually, could you just do the WebRemoteFrame creation and
swap directly inside didCommitProvisionalLoad?

+
+    WebRemoteFrame* remoteFrame = WebRemoteFrame::create(WebTreeScopeType::Document, nullptr);
+    mainFrame->swap(remoteFrame);
+}
+
 void swapAndVerifyFirstChildConsistency(const char* const message, WebFrame* parent, WebFrame* newChild)
 {
     SCOPED_TRACE(message);