aw: Release its reference when the RenderFrameHost is destroyed.

Iframes within a page can be dynamically deleted, triggering the
destruction of the RenderFrameHost (RFH). However, the hosts_ and
hosts_is_in_primary_main_frame_ within the GinJavaBridgeMessageFilter
still hold references to the RFH. This can lead to a continuous
increase in hosts_ and hosts_is_in_primary_main_frame_ when iframes
are frequently created and destroyed

Additionally, when RenderFrameCreated is called, there's no need to
iterate through all frames and attempt to add a filter. We can simply
add a filter to this particular RFH. This approach is more efficient
and easier to understand.

R=​torne@chromium.org

Low-Coverage-Reason: HARD_TO_TEST manually tested on crbug.com/1481603
Bug: 1481603,1481037
Change-Id: I69e80b55e356f59aab68c929cb328e590375a05b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4958082
Reviewed-by: Dave Tapuska <dtapuska@chromium.org>
Auto-Submit: gloam <gaoqingguang@kuaishou.com>
Reviewed-by: Richard (Torne) Coles <torne@chromium.org>
Commit-Queue: Richard (Torne) Coles <torne@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1219036}

• AUTHORS[diff]
• content/browser/android/java/gin_java_bridge_dispatcher_host.cc[diff]
• content/browser/android/java/gin_java_bridge_dispatcher_host.h[diff]
• content/browser/android/java/gin_java_bridge_message_filter.cc[diff]
• content/browser/android/java/gin_java_bridge_message_filter.h[diff]