Convert main_render_frame_ to raw pointer in RenderViewImpl.

content/renderer/render_frame_impl.cc

Index: content/renderer/render_frame_impl.cc
diff --git a/content/renderer/render_frame_impl.cc b/content/renderer/render_frame_impl.cc
index b44691dc57a9f4df6a18592fbf89559507476de8..ad6e528c87bbb44f57f03ec2d774b92efc48073b 100644
--- a/content/renderer/render_frame_impl.cc
+++ b/content/renderer/render_frame_impl.cc
@@ -730,12 +730,18 @@ RenderFrameImpl::~RenderFrameImpl() {
     render_view_->UnregisterVideoHoleFrame(this);
 #endif
 
-  // RenderFrameProxy is only "owned" by RenderFrameImpl in the case it is the
-  // main frame. Ensure it is deleted along with this object.
-  if (!is_subframe_ && render_frame_proxy_) {
-    // The following method calls back into this object and clears
-    // |render_frame_proxy_|.
-    render_frame_proxy_->frameDetached();
+  if (!is_subframe_) {
+    // RenderFrameProxy is "owned" by RenderFrameImpl in the case it is
+    // the main frame. Ensure it is deleted along with this object.
+    if (render_frame_proxy_) {
+      // The following method calls back into this object and clears
+      // |render_frame_proxy_|.
+      render_frame_proxy_->frameDetached();
+    }
+
+    // Since this is the main frame, the RenderViewImpl pointer to this object
+    // must be cleared, otherwise it will result in use-after-free bugs.
+    render_view_->main_render_frame_ = nullptr;
   }
 
   render_view_->UnregisterRenderFrame(this);
@@ -2231,10 +2237,8 @@ void RenderFrameImpl::frameDetached(blink::WebFrame* frame) {
   frame->close();
   frame_ = nullptr;
 
-  if (is_subframe_) {
-    delete this;
-    // Object is invalid after this point.
-  }
+  delete this;
+  // Object is invalid after this point.
 }
 
 void RenderFrameImpl::frameFocused() {
@@ -2643,6 +2647,11 @@ void RenderFrameImpl::didCommitProvisionalLoad(
     CHECK(proxy);
     proxy->web_frame()->swap(frame_);
     proxy_routing_id_ = MSG_ROUTING_NONE;
+
+    // If this is the main frame going from a remote frame to a local frame,
+    // it needs to set RenderViewImpl's pointer for the main frame to itself.
+    if (!is_subframe_)
+      render_view_->main_render_frame_ = this;

[lfg, 2015/05/08 19:42:27]

Consider adding a CHECK or DCHECK that there's no previous main_render_frame_.
It shouldn't, since it's a RemoteFrame going to LocalFrame, but might be good
just for sanity.

[nasko, 2015/05/11 16:12:33]

Done.

   }
 
   // When we perform a new navigation, we need to update the last committed