PepperPlatformAudioInputImpl: support audio input device selection.

ppapi/shared_impl/ppb_audio_input_shared.cc

Index: ppapi/shared_impl/ppb_audio_input_shared.cc
diff --git a/ppapi/shared_impl/ppb_audio_input_shared.cc b/ppapi/shared_impl/ppb_audio_input_shared.cc
index 30288947158be23bd0bb31c28d73b812e7bb3ee0..63da16a6a858a469b7f95d29e05cb9cbfaf97ff1 100644
--- a/ppapi/shared_impl/ppb_audio_input_shared.cc
+++ b/ppapi/shared_impl/ppb_audio_input_shared.cc
@@ -91,17 +91,30 @@ PP_Bool PPB_AudioInput_Shared::StartCapture() {
   if (capturing_)
     return PP_TRUE;
 
+  // If the audio input device hasn't been opened, set |capturing_| to true and
+  // return directly. Capturing will be started once the open operation is
+  // completed.
+  if (open_state_ == BEFORE_OPEN) {
+    capturing_ = true;
+    return PP_TRUE;
+  }
+
   return InternalStartCapture();
 }
 
 PP_Bool PPB_AudioInput_Shared::StopCapture() {
-  if (open_state_ == CLOSED || (open_state_ == BEFORE_OPEN &&
-                                !TrackedCallback::IsPending(open_callback_))) {
+  if (open_state_ == CLOSED)
     return PP_FALSE;
-  }
   if (!capturing_)
     return PP_TRUE;
 
+  // If the audio input device hasn't been opened, set |capturing_| to false and
+  // return directly.
+  if (open_state_ == BEFORE_OPEN) {
+    capturing_ = false;
+    return PP_TRUE;
+  }
+
   return InternalStopCapture();
 }
 
@@ -150,6 +163,7 @@ void PPB_AudioInput_Shared::OnOpenComplete(
     // Clean up the handles.
     base::SyncSocket temp_socket(socket_handle);
     base::SharedMemory temp_mem(shared_memory_handle, false);
+    capturing_ = false;
   }
 
   // The callback may have been aborted by Close().