Adds Analog Gain Control (AGC) to the WebRTC client.

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 149d4b8b12fd64f9a3f6913d8f75ed91a9567f27..8828b42d4ce31667dca1dc7ed62d8d417d78cc24 100644
--- a/content/browser/renderer_host/media/audio_input_renderer_host.cc
+++ b/content/browser/renderer_host/media/audio_input_renderer_host.cc
@@ -176,6 +176,8 @@ bool AudioInputRendererHost::OnMessageReceived(const IPC::Message& message,
     IPC_MESSAGE_HANDLER(AudioInputHostMsg_CloseStream, OnCloseStream)
     IPC_MESSAGE_HANDLER(AudioInputHostMsg_GetVolume, OnGetVolume)
     IPC_MESSAGE_HANDLER(AudioInputHostMsg_SetVolume, OnSetVolume)
+    IPC_MESSAGE_HANDLER(AudioInputHostMsg_SetAutomaticGainControl,
+        OnSetAutomaticGainControl)
     IPC_MESSAGE_UNHANDLED(handled = false)
   IPC_END_MESSAGE_MAP_EX()
 
@@ -200,7 +202,8 @@ void AudioInputRendererHost::OnStartDevice(int stream_id, int session_id) {
 
 void AudioInputRendererHost::OnCreateStream(int stream_id,
                                             const AudioParameters& params,
-                                            const std::string& device_id) {
+                                            const std::string& device_id,
+                                            bool automatic_gain_control) {
   VLOG(1) << "AudioInputRendererHost::OnCreateStream(stream_id="
           << stream_id << ")";
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
@@ -214,9 +217,11 @@ void AudioInputRendererHost::OnCreateStream(int stream_id,
   // Create a new AudioEntry structure.
   scoped_ptr<AudioEntry> entry(new AudioEntry());
 
+  uint32 mem_size = AudioInputBuffer::kSizeOfStructMinusArr + packet_size;

[tommi (sloooow) - chröme, 2012/03/16 13:31:05]

nit: change kSizeOfStructMinusArr -> kSizeOfStructMinusArray.
If I wrote it as "Arr" on the white board, it was just me being lazy :)

I wonder if we can use more specific term than 'array'.  What about using the
word 'Packet' to be consistent with audio_params.GetPacketSize()?

[henrika (OOO until Aug 14), 2012/03/21 10:16:04]

Done.

+
   // Create the shared memory and share it with the renderer process
   // using a new SyncWriter object.
-  if (!entry->shared_memory.CreateAndMapAnonymous(packet_size)) {
+  if (!entry->shared_memory.CreateAndMapAnonymous(mem_size)) {
     // If creation of shared memory failed then send an error message.
     SendErrorMessage(stream_id);
     return;
@@ -248,6 +253,9 @@ void AudioInputRendererHost::OnCreateStream(int stream_id,
     return;
   }
 
+  // Set the initial AGC state for the audio input stream.
+  entry->controller->SetAutomaticGainControl(automatic_gain_control);
+
   // If we have created the controller successfully create a entry and add it
   // to the map.
   entry->stream_id = stream_id;
@@ -290,11 +298,15 @@ void AudioInputRendererHost::OnSetVolume(int stream_id, double volume) {
     return;
   }
 
-  // TODO(henrika): TBI.
-  NOTIMPLEMENTED();
+  entry->controller->SetVolume(volume);
 }
 
 void AudioInputRendererHost::OnGetVolume(int stream_id) {
+  NOTIMPLEMENTED();

[tommi (sloooow) - chröme, 2012/03/16 13:31:05]

Do we need to implement this at some point or never?
(when is it called?)

[scherkus (not reviewing), 2012/03/20 13:49:41]

AFAIK GetVolume() is completely unused

[henrika (OOO until Aug 14), 2012/03/21 10:16:04]

Yeah, you are correct. I might as well drop it actually. Better to add it
if/when we need it.

+}
+
+void AudioInputRendererHost::OnSetAutomaticGainControl(int stream_id,
+                                                       bool enabled) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
 
   AudioEntry* entry = LookupById(stream_id);
@@ -303,8 +315,7 @@ void AudioInputRendererHost::OnGetVolume(int stream_id) {
     return;
   }
 
-  // TODO(henrika): TBI.
-  NOTIMPLEMENTED();
+  entry->controller->SetAutomaticGainControl(enabled);
 }
 
 void AudioInputRendererHost::SendErrorMessage(int stream_id) {