Reland of OOPIF: Call setCoreFrame on remote-to-local swaps.

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..418560efdcac9bdb4acd30535ba5368341a4d031 100644
--- a/Source/web/tests/WebFrameTest.cpp
+++ b/Source/web/tests/WebFrameTest.cpp
@@ -7815,6 +7815,32 @@
     view->close();
 }
 
+// See https://crbug.com/525285.
+TEST_P(ParameterizedWebFrameTest, RemoteToLocalSwapOnMainFrameInitializesCoreFrame)
+{
+    FrameTestHelpers::TestWebViewClient viewClient;
+    FrameTestHelpers::TestWebRemoteFrameClient remoteClient;
+    WebView* view = WebView::create(&viewClient);
+    view->setMainFrame(remoteClient.frame());
+    WebRemoteFrame* remoteRoot = view->mainFrame()->toWebRemoteFrame();
+    remoteRoot->setReplicatedOrigin(SecurityOrigin::createUnique());
+
+    FrameTestHelpers::TestWebFrameClient localFrameClient;
+    remoteRoot->createLocalChild(WebTreeScopeType::Document, "", WebSandboxFlags::None, &localFrameClient, nullptr);
+
+    // Do a remote-to-local swap of the top frame.
+    FrameTestHelpers::TestWebFrameClient localClient;
+    WebLocalFrame* localRoot = WebLocalFrame::create(WebTreeScopeType::Document, &localClient);
+    localRoot->initializeToReplaceRemoteFrame(remoteRoot, "", WebSandboxFlags::None);
+    remoteRoot->swap(localRoot);
+
+    // Load a page with a child frame in the new root to make sure this doesn't
+    // crash when the child frame invokes setCoreFrame.
+    FrameTestHelpers::loadFrame(localRoot, "data:text/html,<iframe></iframe>");
+
+    view->close();
+}
+
 class OverscrollWebViewClient : public FrameTestHelpers::TestWebViewClient {
 public:
     MOCK_METHOD4(didOverscroll, void(const WebFloatSize&, const WebFloatSize&, const WebFloatPoint&, const WebFloatSize&));