GitLab

Fix an issue triggered on cross-process navigations that would result
in UrlRequestRewriteRulesManager incorrectly keeping track of live
RenderFrameHosts for a given Frame. This happens because cross-process
navigations trigger a RenderFrameCreated even for a FrameTreeNode ID
before the RenderFrameDeleted event for the older RenderFrameHost. The
sequence goes like this:
* Frame creation
  * Tracking RFH IDs: []
* RenderFrameCreated(0x1810) with FrameTreeNode ID 2.
  * Tracking RFH IDs: [2]
* RenderFrameCreated(0xa410) with FrameTreeNode ID 2.
  * Tracking RFH IDs: [2]
* RenderFrameDeleted(0x1810) with FrameTreeNode ID 2.
  * Tracking RFH IDs: []
* RenderFrameDeleted(0xa410) with FrameTreeNode ID 2.
  * At this point, the DCHECK is triggered because there is no RFH
    with ID 2 being tracked.

The map now keeps track of the currently active RenderFrameHost for a
given FrameTreeNode ID so we can now know when it is safe to ignore a
"second" RenderFrameDeleted event for the same FrameTreeNode ID.

Bug: 1014281
Test: Load gmail.com -> Refresh -> No DCHECK triggered.
Change-Id: I82ce437c8c45984c695658d0e2d7deea45aad63e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1864023
Commit-Queue: Fabrice de Gans-Riberi <fdegans@chromium.org>
Reviewed-by: Wez <wez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#707493}