Add AudioStreamRegistry. Move stream counting logic

content/browser/renderer_host/render_process_host_impl.h

Index: content/browser/renderer_host/render_process_host_impl.h
diff --git a/content/browser/renderer_host/render_process_host_impl.h b/content/browser/renderer_host/render_process_host_impl.h
index 0dd50c3a1cd36946022c7188e5722ada40ce82a6..dfd3719207ce6fe13edb9a419928b32c777c3d0f 100644
--- a/content/browser/renderer_host/render_process_host_impl.h
+++ b/content/browser/renderer_host/render_process_host_impl.h
@@ -52,6 +52,7 @@ class SharedPersistentMemoryAllocator;
 namespace content {
 class AudioInputRendererHost;
 class AudioRendererHost;
+class AudioStreamRegistryImpl;
 class ChildConnection;
 class InProcessChildThreadParams;
 class MessagePortMessageFilter;
@@ -529,6 +530,9 @@ class CONTENT_EXPORT RenderProcessHostImpl
   // through RenderProcessHostObserver::RenderProcessExited.
   bool within_process_died_observer_;
 
+  std::unique_ptr<AudioStreamRegistryImpl, BrowserThread::DeleteOnIOThread>
+      audio_stream_registry_;
+
   scoped_refptr<AudioRendererHost> audio_renderer_host_;
 
   scoped_refptr<AudioInputRendererHost> audio_input_renderer_host_;