Replace ForEachFrame with GetMainFrame()->ForEachRenderFrameHost.

The JS dispatching bridge is used for WebView and WebLayer from Android.
These environments do not support back/forward cache nor prerender so
converting to GetMainFrame()->ForEachRenderFrameHost is correct and
conveys the intent of the method.

BUG=1208438

Change-Id: I22be31a3985df8255db568f0ed12750972689f0d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3381934


Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: Richard Coles <torne@chromium.org>
Commit-Queue: Dave Tapuska <dtapuska@chromium.org>
Cr-Commit-Position: refs/heads/main@{#958212}