Browser-wide audio mirroring for TabCapture API

media/audio/audio_input_controller.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/audio/audio_input_controller.h"
 
 #include "base/bind.h"
 #include "base/threading/thread_restrictions.h"
 #include "media/base/limits.h"
 
@@ skipping 130 matching lines @@
     stream_->Close();
     stream_ = NULL;
     // TODO(satish): Define error types.
     handler_->OnError(this, 0);
     return;
   }
 
   DCHECK(!no_data_timer_.get());
   // Create the data timer which will call DoCheckForNoData(). The timer
   // is started in DoRecord() and restarted in each DoCheckForNoData() callback.
-  no_data_timer_.reset(new base::Timer(
-      FROM_HERE, base::TimeDelta::FromSeconds(kTimerInitialIntervalSeconds),
-      base::Bind(&AudioInputController::DoCheckForNoData,
-      base::Unretained(this)), false));
+  if (params.format() != AudioParameters::AUDIO_MIRROR_BROWSER) {

[Alpha Left Google, 2012/11/28 01:04:47]

Why special case for audio mirroring? You can give empty buffers for silence.
It's better not to have knowledge what type of audio content passes through this
class.

[justinlin, 2012/11/28 14:30:31]

In a previous iteration, this was causing crashes for some reason, but I don't
see them anymore. Reverted this class. 

+    no_data_timer_.reset(new base::Timer(
+        FROM_HERE, base::TimeDelta::FromSeconds(kTimerInitialIntervalSeconds),
+        base::Bind(&AudioInputController::DoCheckForNoData,
+        base::Unretained(this)), false));
+  }
   state_ = kCreated;
   handler_->OnCreated(this);
 }
 
 void AudioInputController::DoRecord() {
   DCHECK(message_loop_->BelongsToCurrentThread());
 
   if (state_ != kCreated)
     return;
 
   {
     base::AutoLock auto_lock(lock_);
     state_ = kRecording;
   }
 
   // Start the data timer. Once |kTimerResetIntervalSeconds| have passed,
   // a callback to DoCheckForNoData() is made.
-  no_data_timer_->Reset();
+  if (no_data_timer_.get())
+    no_data_timer_->Reset();
 
   stream_->Start(this);
   handler_->OnRecording(this);
 }
 
 void AudioInputController::DoClose() {
   DCHECK(message_loop_->BelongsToCurrentThread());
 
   // Delete the timer on the same thread that created it.
   no_data_timer_.reset();
@@ skipping 60 matching lines @@
     return;
   }
 
   // Mark data as non-active. The flag will be re-enabled in OnData() each
   // time a data packet is received. Hence, under normal conditions, the
   // flag will only be disabled during a very short period.
   SetDataIsActive(false);
 
   // Restart the timer to ensure that we check the flag again in
   // |kTimerResetIntervalSeconds|.
-  no_data_timer_->Start(
-      FROM_HERE, base::TimeDelta::FromSeconds(kTimerResetIntervalSeconds),
-      base::Bind(&AudioInputController::DoCheckForNoData,
-      base::Unretained(this)));
+  if (no_data_timer_.get())
+    no_data_timer_->Start(
+        FROM_HERE, base::TimeDelta::FromSeconds(kTimerResetIntervalSeconds),
+        base::Bind(&AudioInputController::DoCheckForNoData,
+        base::Unretained(this)));
 }
 
 void AudioInputController::OnData(AudioInputStream* stream, const uint8* data,
                                   uint32 size, uint32 hardware_delay_bytes,
                                   double volume) {
   {
     base::AutoLock auto_lock(lock_);
     if (state_ != kRecording)
       return;
   }
@@ skipping 43 matching lines @@
 
 void AudioInputController::SetDataIsActive(bool enabled) {
   base::subtle::Release_Store(&data_is_active_, enabled);
 }
 
 bool AudioInputController::GetDataIsActive() {
   return (base::subtle::Acquire_Load(&data_is_active_) != false);
 }
 
 }  // namespace media