Use multiple shared memory buffers cyclically for audio capture.

content/renderer/media/audio_input_message_filter.cc

Index: content/renderer/media/audio_input_message_filter.cc
===================================================================
--- content/renderer/media/audio_input_message_filter.cc	(revision 185810)
+++ content/renderer/media/audio_input_message_filter.cc	(working copy)
@@ -46,6 +46,8 @@
   IPC_BEGIN_MESSAGE_MAP(AudioInputMessageFilter, message)
     IPC_MESSAGE_HANDLER(AudioInputMsg_NotifyStreamCreated,
                         OnStreamCreated)
+    IPC_MESSAGE_HANDLER(AudioInputMsg_NotifySharedMemoryCreated,
+                        OnSharedMemoryCreated)
     IPC_MESSAGE_HANDLER(AudioInputMsg_NotifyStreamVolume, OnStreamVolume)
     IPC_MESSAGE_HANDLER(AudioInputMsg_NotifyStreamStateChanged,
                         OnStreamStateChanged)
@@ -88,13 +90,12 @@
 
 void AudioInputMessageFilter::OnStreamCreated(
     int stream_id,
-    base::SharedMemoryHandle handle,
 #if defined(OS_WIN)
     base::SyncSocket::Handle socket_handle,
 #else
     base::FileDescriptor socket_descriptor,
 #endif
-    uint32 length) {
+    uint32 total_handles) {
   DCHECK(io_message_loop_->BelongsToCurrentThread());
 
 #if !defined(OS_WIN)
@@ -104,14 +105,31 @@
   if (!delegate) {
     DLOG(WARNING) << "Got audio stream event for a non-existent or removed"
                   << " audio capturer (stream_id=" << stream_id << ").";
-    base::SharedMemory::CloseHandle(handle);
     base::SyncSocket socket(socket_handle);
     return;
   }
   // Forward message to the stream delegate.
-  delegate->OnStreamCreated(handle, socket_handle, length);
+  delegate->OnStreamCreated(socket_handle, total_handles);
 }
 
+void AudioInputMessageFilter::OnSharedMemoryCreated(
+    int stream_id,
+    base::SharedMemoryHandle handle,
+    uint32 length,
+    uint32 handle_index) {
+  DCHECK(io_message_loop_->BelongsToCurrentThread());
+
+  media::AudioInputIPCDelegate* delegate = delegates_.Lookup(stream_id);
+  if (!delegate) {
+    DLOG(WARNING) << "Got audio stream event for a non-existent or removed"
+                  << " audio capturer (stream_id=" << stream_id << ").";
+    base::SharedMemory::CloseHandle(handle);
+    return;
+  }
+  // Forward message to the stream delegate.
+  delegate->OnSharedMemoryCreated(handle, length, handle_index);
+}
+
 void AudioInputMessageFilter::OnStreamVolume(int stream_id, double volume) {
   DCHECK(io_message_loop_->BelongsToCurrentThread());
   media::AudioInputIPCDelegate* delegate = delegates_.Lookup(stream_id);
@@ -160,9 +178,11 @@
 void AudioInputMessageFilter::CreateStream(int stream_id,
                                            const media::AudioParameters& params,
                                            const std::string& device_id,
-                                           bool automatic_gain_control) {
+                                           bool automatic_gain_control,
+                                           int shared_memory_count) {
   Send(new AudioInputHostMsg_CreateStream(
-      stream_id, params, device_id, automatic_gain_control));
+      stream_id, params, device_id, automatic_gain_control,
+      shared_memory_count));
 }
 
 void AudioInputMessageFilter::AssociateStreamWithConsumer(int stream_id,