Remove usage of FrameTreeNode IDs (see issue #2421)

With the introduction of prerendering in Chromium it is now possible for
RenderFrameHosts (RFH) to move between FrameTrees. As a consequence we can no
longer rely on FrameTreeNode IDs to uniquely identify a RFH over its lifespan.
We must now switch to using GlobalRenderFrameHostId (child_id, frame_routing_id)
instead for that purpose. Additionally, we simplify existing code by using the
GlobalRenderFrameHostId struct in all places that previously used a
(render_process_id, render_frame_id) pair, since these concepts are equivalent.

See https://crbug.com/1179502#c8 for additional background.

libcef/browser/request_context_impl.h

@@ -12,6 +12,10 @@
 #include "libcef/browser/net_service/cookie_manager_impl.h"
 #include "libcef/browser/thread_util.h"
 
+namespace content {
+struct GlobalRenderFrameHostId;
+}
+
 class CefBrowserContext;
 
 // Implementation of the CefRequestContext interface. All methods are thread-
@@ -95,18 +99,14 @@ class CefRequestContextImpl : public CefRequestContext {
   // Called from CefBrowserContentsDelegate::RenderFrameCreated or
   // CefMimeHandlerViewGuestDelegate::OnGuestAttached when a render frame is
   // created.
-  void OnRenderFrameCreated(int render_process_id,
-                            int render_frame_id,
-                            int frame_tree_node_id,
+  void OnRenderFrameCreated(const content::GlobalRenderFrameHostId& global_id,
                             bool is_main_frame,
                             bool is_guest_view);
 
   // Called from CefBrowserContentsDelegate::RenderFrameDeleted or
   // CefMimeHandlerViewGuestDelegate::OnGuestDetached when a render frame is
   // deleted.
-  void OnRenderFrameDeleted(int render_process_id,
-                            int render_frame_id,
-                            int frame_tree_node_id,
+  void OnRenderFrameDeleted(const content::GlobalRenderFrameHostId& global_id,
                             bool is_main_frame,
                             bool is_guest_view);