Snapshot a pointer to the main frame when creating WebViewFrameWidget.

Otherwise, invoking WebViewFrameWidget::close() from frame swap will
result in trying to clear the frame widget on the wrong main frame.

Other miscellaneous fixes:
- WebViewFrameWidget now uses smart pointers where appropriate for its
  members.
- WebViewFrameWidget's ctor also takes a WebWidgetClient* pointer.
  This is future-proofing to help merge the widget implementations in
  WebFrameWidget and WebView.

BUG=419087

Review URL: https://codereview.chromium.org/1310063002

git-svn-id: svn://svn.chromium.org/blink/trunk@201048 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/web/WebFrameWidgetImpl.cpp

@@ -65,9 +65,9 @@ WebFrameWidget* WebFrameWidget::create(WebWidgetClient* client, WebLocalFrame* l
     return WebFrameWidgetImpl::create(client, localRoot);
 }
 
-WebFrameWidget* WebFrameWidget::create(WebView* webView)
+WebFrameWidget* WebFrameWidget::create(WebWidgetClient* client, WebView* webView, WebLocalFrame* mainFrame)
 {
-    return new WebViewFrameWidget(*toWebViewImpl(webView));
+    return new WebViewFrameWidget(client, toWebViewImpl(*webView), toWebLocalFrameImpl(*mainFrame));
 }
 
 WebFrameWidgetImpl* WebFrameWidgetImpl::create(WebWidgetClient* client, WebLocalFrame* localRoot)

third_party/WebKit/Source/web/WebViewFrameWidget.cpp

@@ -10,9 +10,10 @@
 
 namespace blink {
 
-WebViewFrameWidget::WebViewFrameWidget(WebViewImpl& webView) : m_webView(&webView)
+WebViewFrameWidget::WebViewFrameWidget(WebWidgetClient* client, WebViewImpl& webView, WebLocalFrameImpl& mainFrame)
+    : m_client(client), m_webView(&webView), m_mainFrame(&mainFrame)
 {
-    m_webView->mainFrameImpl()->setFrameWidget(this);
+    m_mainFrame->setFrameWidget(this);
 }
 
 WebViewFrameWidget::~WebViewFrameWidget()
@@ -21,8 +22,14 @@ WebViewFrameWidget::~WebViewFrameWidget()
 
 void WebViewFrameWidget::close()
 {
-    m_webView->mainFrameImpl()->setFrameWidget(nullptr);
+    // Note: it's important to use the captured main frame pointer here. During
+    // a frame swap, the swapped frame is detached *after* the frame tree is
+    // updated. If the main frame is being swapped, then
+    // m_webView()->mainFrameImpl() will no longer point to the original frame.
+    m_mainFrame->setFrameWidget(nullptr);
+    m_mainFrame = nullptr;
     m_webView = nullptr;
+    m_client = nullptr;
 
     // Note: this intentionally does not forward to WebView::close(), to make it
     // easier to untangle the cleanup logic later.

third_party/WebKit/Source/web/WebViewFrameWidget.h

@@ -5,12 +5,16 @@
 #ifndef WebViewFrameWidget_h
 #define WebViewFrameWidget_h
 
+#include "platform/heap/Handle.h"
 #include "public/web/WebFrameWidget.h"
 #include "wtf/Noncopyable.h"
+#include "wtf/RefPtr.h"
 
 namespace blink {
 
+class WebLocalFrameImpl;
 class WebViewImpl;
+class WebWidgetClient;
 
 // Shim class to help normalize the widget interfaces in the Blink public API.
 // For OOPI, subframes have WebFrameWidgets for input and rendering.
@@ -30,7 +34,7 @@ class WebViewImpl;
 class WebViewFrameWidget : public WebFrameWidget {
     WTF_MAKE_NONCOPYABLE(WebViewFrameWidget);
 public:
-    explicit WebViewFrameWidget(WebViewImpl&);
+    explicit WebViewFrameWidget(WebWidgetClient*, WebViewImpl&, WebLocalFrameImpl&);
     virtual ~WebViewFrameWidget();
 
     // WebFrameWidget overrides:
@@ -92,7 +96,9 @@ public:
     bool forSubframe() const { return false; }
 
 private:
-    WebViewImpl* m_webView;
+    WebWidgetClient* m_client;
+    RefPtr<WebViewImpl> m_webView;
+    RefPtrWillBePersistent<WebLocalFrameImpl> m_mainFrame;
 };
 
 } // namespace blink

third_party/WebKit/public/web/WebFrameWidget.h

@@ -46,7 +46,8 @@ public:
     BLINK_EXPORT static WebFrameWidget* create(WebWidgetClient*, WebLocalFrame*);
     // Creates a frame widget for a WebView. Temporary helper to help transition
     // away from WebView inheriting WebWidget.
-    BLINK_EXPORT static WebFrameWidget* create(WebView*);
+    // TODO(dcheng): Remove once transition is complete.
+    BLINK_EXPORT static WebFrameWidget* create(WebWidgetClient*, WebView*, WebLocalFrame* mainFrame);
 
     // Sets the visibility of the WebFrameWidget.
     // We still track page-level visibility, but additionally we need to notify a WebFrameWidget