Add empty Linux implementation of audio_service.

chrome/browser/extensions/api/audio/audio_service_linux.cc

Index: chrome/browser/extensions/api/audio/audio_service_linux.cc
diff --git a/chrome/browser/extensions/api/audio/audio_service_linux.cc b/chrome/browser/extensions/api/audio/audio_service_linux.cc
new file mode 100644
index 0000000000000000000000000000000000000000..b0bd3e6147b4c91fa801febbcfaa9851e1d8f247
--- /dev/null
+++ b/chrome/browser/extensions/api/audio/audio_service_linux.cc
@@ -0,0 +1,87 @@
+// Copyright 2014 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 "chrome/browser/extensions/api/audio/audio_service.h"
+
+#include "base/callback.h"
+#include "base/memory/weak_ptr.h"
+#include "base/observer_list.h"
+#include "base/strings/string_number_conversions.h"
+#include "content/public/browser/browser_thread.h"
+
+using content::BrowserThread;
+
+namespace extensions {
+
+using api::audio::OutputDeviceInfo;
+using api::audio::InputDeviceInfo;
+
+class AudioServiceImpl : public AudioService {
+ public:
+  AudioServiceImpl();
+  virtual ~AudioServiceImpl();
+
+  // Called by listeners to this service to add/remove themselves as observers.
+  virtual void AddObserver(AudioService::Observer* observer) OVERRIDE;
+  virtual void RemoveObserver(AudioService::Observer* observer) OVERRIDE;
+
+  // Start to query audio device information.
+  virtual void StartGetInfo(const GetInfoCallback& callback) OVERRIDE;
+  virtual void SetActiveDevices(const DeviceIdList& device_list) OVERRIDE;
+  virtual bool SetDeviceProperties(const std::string& device_id,
+                                   bool muted,
+                                   int volume,
+                                   int gain) OVERRIDE;
+
+  // List of observers.
+  ObserverList<AudioService::Observer> observer_list_;
+
+  // Note: This should remain the last member so it'll be destroyed and
+  // invalidate the weak pointers before any other members are destroyed.
+  base::WeakPtrFactory<AudioServiceImpl> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(AudioServiceImpl);
+};
+
+AudioServiceImpl::AudioServiceImpl() : weak_ptr_factory_(this) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+}
+
+AudioServiceImpl::~AudioServiceImpl() {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+}
+
+void AudioServiceImpl::AddObserver(AudioService::Observer* observer) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  observer_list_.AddObserver(observer);
+}
+
+void AudioServiceImpl::RemoveObserver(AudioService::Observer* observer) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  observer_list_.RemoveObserver(observer);
+}
+
+void AudioServiceImpl::StartGetInfo(const GetInfoCallback& callback) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  if (!callback.is_null())
+    callback.Run(OutputInfo(), InputInfo(), false);
+}
+
+void AudioServiceImpl::SetActiveDevices(const DeviceIdList& device_list) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+}
+
+bool AudioServiceImpl::SetDeviceProperties(const std::string& device_id,
+                                           bool muted,
+                                           int volume,
+                                           int gain) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  return false;
+}
+
+AudioService* AudioService::CreateInstance() {
+  return new AudioServiceImpl;
+}
+
+}  // namespace extensions