[Cross-Site Isolation] Migrate entire MediaStream verticals to be per-RenderFrame.

content/public/browser/speech_recognition_session_context.h

Index: content/public/browser/speech_recognition_session_context.h
diff --git a/content/public/browser/speech_recognition_session_context.h b/content/public/browser/speech_recognition_session_context.h
index d092a5daf044eb8fb1252b80d98c9c243b669ccc..532a4e47e6533c899452e7d5406862dcff397dc3 100644
--- a/content/public/browser/speech_recognition_session_context.h
+++ b/content/public/browser/speech_recognition_session_context.h
@@ -26,6 +26,7 @@ struct CONTENT_EXPORT SpeechRecognitionSessionContext {
 
   int render_process_id;
   int render_view_id;
+  int render_frame_id;

[jam, 2014/07/15 02:04:08]

it's redundant to have render_view_id and render_frame_id, since
RenderFrameHost::FromID(render_process_id, render_frame_id)->GetRenderViewHost()
provides the RVH. it's problematic to have both RF and RV ID since it could
result in an inconsistent state (where the RenderFrameHost's WC isn't the same
as the RenderViewHost's WC).

can you remove render_view_id and call
RenderFrameHost::FromID(render_process_id, render_frame_id)->GetRenderViewHost()
everywhere that we temporarily need the render view id for now?

[miu, 2014/07/15 20:37:55]

I can't do the conversion in this CL.  It's not as simple as calling
RenderFrameHost::FromID() because the render_view_id is used in a lot of the 
"control" methods that run on the IO thread.  There's a lot of work, and it
could easily be its own 200+ LOC change.

I think this is safe right now, since the Speech Recognition implementation is
mostly unchanged (i.e., RenderView based).  The only reason I added
render_frame_id is so the code could make use of
MediaStreamManager::MakeMediaAccessRequest().  Actually, the Speech Recognition
impl isn't really using MSManager like all the other media code.  It's just
trying to utilize the media permissions UI to request access from the user, then
doing it's own thing separately.  There's a TODO comment in
MediaStreamManager::MakeMediaAccessRequest that hints at a design problem with
this.

 
   // Browser plugin guest's render view id, if this context represents a speech
   // recognition request from an embedder on behalf of the guest. This is used