When BackForwardCache is enabled and the user navigates the main frame
back/forward a new RFH may be created for an existing main frame GlobalId value
and CefFrameHostImpl (e.g. an object that was previously Detach()ed after main
frame navigation called SetMainFrame, but for which RenderFrameDeleted was not
subsequently called due to insertion in the BackForwardCache). In this case we
can re-attach the new RFH to the existing main frame CefFrameHostImpl in
RenderFrameHostStateChanged and resume processing of messages.
Swapping back/forward to an existing (already loaded) renderer does not trigger
new notifications for draggable regions (e.g. RenderFrameObserver::
DraggableRegionsChanged is not called by default). We therefore explicitly
request an update of draggable regions by sending the DidStopLoading message to
the renderer.
A new |reattached| parameter is added to CefFrameHandler::OnFrameAttached to
support identification of BackForwardCache usage by the client.
To test with unit tests:
Run `ceftests --gtest_filter=DraggableRegionsTest.DraggableRegionsCrossOrigin
--enable-features=BackForwardCache`
To test manually:
1. Run `cefclient --enable-features=BackForwardCache --use-views
--url=http://tests/draggable`, note that draggable regions work.
2. Load https://www.google.com via the address bar, note that draggable regions
are removed.
3. Go back to http://tests/draggable, note that draggable regions work.
4. Go forward to https://www.google.com, note that draggable regions are
removed.
See the new cef_frame_handler.h for complete usage documentation.
This change includes the following related enhancements:
- The newly added CefBrowser::IsValid method will return false (in the browser
process) after CefLifeSpanHandler::OnBeforeClose is called.
- CefBrowser::GetMainFrame will return a valid object (in the browser process)
until after CefLifeSpanHandler::OnBeforeClose is called.
- The main frame object will change during cross-origin navigation or
re-navigation after renderer process termination. During that time,
GetMainFrame will return the new/pending frame (in the browser process) and
any messages that arrive for the new/pending frame will be correctly
attributed in OnProcessMessageReceived.
- Commands to be executed in the renderer process that may fail during early
frame initialization (ExecuteJavaScript, LoadRequest, etc.) will now be
queued until after the JavaScript context for the frame has been created.
- Logging has been added for any commands that are dropped because they arrived
after frame detachment.
