chrome: Update expectations with same-site BFCache enabled (fixes issue #3301)

With same-site BFCache enabled every navigation can now potentially be served
via the BFCache. To support this internally a new top-level RenderFrame object
may be created for each new navigation. As a result, OnBrowserCreated may now
be called multiple times with the same browser ID in a given renderer process
(a behavior previously only seen with cross-site navigations and different
renderer processes).

BFCache navigations do not trigger the same Chromium notifications as a normal
load. To avoid breaking CEF API usage expectations we now synthetically
generate the load-related callbacks that would otherwise be missing
(OnLoadingStateChange with isLoading=true, OnLoadStart, OnLoadEnd). The
|httpStatusCode| argument to OnLoadEnd will be 0 in this case.

To test:
- Run `FrameHandlerTest.*:MessageRouterTest.*:NavigationTest.*`
- Run `NavigationTest.LoadSameOriginLoadURL` for OnBrowserCreated behavior.
- Run `NavigationTest.History` for load-related callback behavior.

libcef/renderer/browser_impl.h

@@ -92,6 +92,7 @@ class CefBrowserImpl : public CefBrowser, public blink::WebViewObserver {
   void FrameDetached(int64_t frame_id);
 
   void OnLoadingStateChange(bool isLoading);
+  void OnEnterBFCache();
 
  private:
   // ID of the browser that this RenderView is associated with. During loading
@@ -105,6 +106,9 @@ class CefBrowserImpl : public CefBrowser, public blink::WebViewObserver {
   using FrameMap = std::map<int64, CefRefPtr<CefFrameImpl>>;
   FrameMap frames_;
 
+  // True if the browser was in the BFCache.
+  bool was_in_bfcache_ = false;
+
   // Map of unique frame ids to CefTrackManager objects that need to be cleaned
   // up when the frame is deleted.
   using FrameObjectMap = std::map<int64, CefRefPtr<CefTrackManager>>;