[content] Fix confusing documentation.

The RenderFrameHost documentation says that using GlobalRenderFrameHostId is the preferred way, but the documentation on that method says that GlobalRenderFrameHostToken is the preferred way. Cleanup documentation so that it is clear the token version is superior.

Change-Id: I362df8b3288feb5d6405afe9cd83e3be6c3fbdf1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5970216
Reviewed-by: Patrick Monette <pmonette@chromium.org>
Commit-Queue: Dave Tapuska <dtapuska@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1374680}

content/public/browser/render_frame_host.h

@@ -128,8 +128,8 @@ class Page;
 
 // The interface provides a communication conduit with a frame in the renderer.
 // The preferred way to keep a reference to a RenderFrameHost is storing a
-// GlobalRenderFrameHostId and using RenderFrameHost::FromID() when you need to
-// access it.
+// GlobalRenderFrameHostToken and using RenderFrameHost::FromFrameToken() when
+// you need to access it.
 //
 // Any code that uses RenderFrameHost must be aware of back-forward cache, see
 // LifecycleState. The main side-effect is that any IPCs that are processed on a