Add a basic test for main frame swap.

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 edf9a86ff32ccf5e848305e7d73f3b183716cf8a..8b22ea1c520fdb0823513a9c233e16e626c4744d 100644
--- a/Source/web/tests/WebFrameTest.cpp
+++ b/Source/web/tests/WebFrameTest.cpp
@@ -6525,10 +6525,28 @@ private:
     FrameTestHelpers::WebViewHelper m_webViewHelper;
 };
 
-// FIXME: We should have tests for main frame swaps, but it interacts poorly
-// with the geolocation inspector agent, since the lifetime of the inspector
-// agent is tied to the Page, but the inspector agent is created by the
-// instantiation of the main frame.
+TEST_F(WebFrameSwapTest, SwapMainFrame)
+{
+    WebFrame* remoteFrame = WebRemoteFrame::create(0);
+    mainFrame()->swap(remoteFrame);
+
+    FrameTestHelpers::TestWebFrameClient client;
+    WebFrame* localFrame = WebLocalFrame::create(&client);
+    remoteFrame->swap(localFrame);
+
+    // FIXME: This almost certainly fires more load events on the iframe element
+    // than it should.

[Nate Chapin, 2014/10/16 21:17:46]

This comment seems out of place?

[dcheng, 2014/10/16 21:20:20]

It's about the call to loadFrame() below... but I don't recall why this fires
too many load events anymore (or if it even does).

[Nate Chapin, 2014/10/16 21:21:47]

Well, maybe I'm missing something, but I don't see any evidence of an iframe
anywhere in this test, so I don't understand how we could be firing load events
on one.

[dcheng, 2014/10/16 21:23:22]

Hm. Good point. I've removed this FIXME.

+    // Finally, make sure an embedder triggered load in the local frame swapped
+    // back in works.
+    FrameTestHelpers::loadFrame(localFrame, m_baseURL + "subframe-hello.html");
+    std::string content = localFrame->contentAsText(1024).utf8();
+    EXPECT_EQ("hello", content);
+
+    // Manually reset to break WebViewHelper's dependency on the stack allocated
+    // TestWebFrameClient.
+    reset();
+    remoteFrame->close();
+}
 
 void swapAndVerifyFirstChildConsistency(const char* const message, WebFrame* parent, WebFrame* newChild)
 {