Allow MessageFilters to restrict listening to specific message classes

content/browser/renderer_host/media/audio_input_renderer_host.cc

Index: content/browser/renderer_host/media/audio_input_renderer_host.cc
diff --git a/content/browser/renderer_host/media/audio_input_renderer_host.cc b/content/browser/renderer_host/media/audio_input_renderer_host.cc
index 93ed16ce07f03a06818ef1c639eff604ba962498..42bb8dee68cd50b0ec7c83e937dcdb71cc17564c 100644
--- a/content/browser/renderer_host/media/audio_input_renderer_host.cc
+++ b/content/browser/renderer_host/media/audio_input_renderer_host.cc
@@ -17,6 +17,11 @@
 #include "media/audio/audio_manager_base.h"
 
 namespace content {
+namespace {
+const uint32 kFilteredMessageClasses[] = {
+  AudioMsgStart,
+};
+}
 
 struct AudioInputRendererHost::AudioEntry {
   AudioEntry();
@@ -54,7 +59,9 @@ AudioInputRendererHost::AudioInputRendererHost(
     MediaStreamManager* media_stream_manager,
     AudioMirroringManager* audio_mirroring_manager,
     media::UserInputMonitor* user_input_monitor)
-    : audio_manager_(audio_manager),
+    : BrowserMessageFilter(
+          kFilteredMessageClasses, arraysize(kFilteredMessageClasses)),
+      audio_manager_(audio_manager),
       media_stream_manager_(media_stream_manager),
       audio_mirroring_manager_(audio_mirroring_manager),
       user_input_monitor_(user_input_monitor),