Support audio output device enumeration and selection in PPAPI

- Keep the current |PPB_Audio| interface unchanged
- Add a new dev interface: |PPB_AudioOutput_Dev|
- Implement |PPB_AudioOutput_Dev| using the typical HostResource
  implementations like |PPB_AudioInput_Dev|
- Add ppapi/proxy/audio_output_resource.h/cc etc. to implement
  |AudioOutputResource|
- Add content/renderer/pepper/pepper_audio_output_host.h/cc etc.
  to implement |PepperAudioOutputHost|
- Keep ppb_audio_proxy.h/cc, ppb_audio_shared.h/cc, ppb_audio_impl.h/cc
  unchanged, so that the current |PPB_Audio| will not be affected.
- Modify content/renderer/pepper/pepper_platform_audio_output.h/cc to
  accept both |AudioHelper| and |PepperAudioOutputHost| clients
- The way to implement |PepperAudioOutputHost| is borrowed from
  "media/audio/audio_output_device.cc" where audio output selection isi
  supported for javascript.
- Add necessary IPC message definitions for |PPB_AudioOutput_Dev|

BUG=701584
R= bbudge@chromium.org, tsepez@chromium.org, isherman@chromium.org

Review-Url: https://codereview.chromium.org/2755613002
Cr-Commit-Position: refs/heads/master@{#462889}

chrome/common/ppapi_utils.cc

@@ -7,6 +7,7 @@
 
 #include "build/build_config.h"
 #include "ppapi/c/dev/ppb_audio_input_dev.h"
+#include "ppapi/c/dev/ppb_audio_output_dev.h"
 #include "ppapi/c/dev/ppb_buffer_dev.h"
 #include "ppapi/c/dev/ppb_char_set_dev.h"
 #include "ppapi/c/dev/ppb_crypto_dev.h"

content/renderer/BUILD.gn

@@ -792,6 +792,8 @@ target(link_target_type, "renderer") {
       "pepper/pepper_audio_encoder_host.h",
       "pepper/pepper_audio_input_host.cc",
       "pepper/pepper_audio_input_host.h",
+      "pepper/pepper_audio_output_host.cc",
+      "pepper/pepper_audio_output_host.h",
       "pepper/pepper_broker.cc",
       "pepper/pepper_broker.h",
       "pepper/pepper_browser_connection.cc",
@@ -822,6 +824,8 @@ target(link_target_type, "renderer") {
       "pepper/pepper_platform_audio_input.h",
       "pepper/pepper_platform_audio_output.cc",
       "pepper/pepper_platform_audio_output.h",
+      "pepper/pepper_platform_audio_output_dev.cc",
+      "pepper/pepper_platform_audio_output_dev.h",
       "pepper/pepper_platform_camera_device.cc",
       "pepper/pepper_platform_camera_device.h",
       "pepper/pepper_platform_video_capture.cc",

content/renderer/pepper/content_renderer_pepper_host_factory.cc

@@ -15,6 +15,7 @@
 #include "content/public/renderer/content_renderer_client.h"
 #include "content/renderer/pepper/pepper_audio_encoder_host.h"
 #include "content/renderer/pepper/pepper_audio_input_host.h"
+#include "content/renderer/pepper/pepper_audio_output_host.h"
 #include "content/renderer/pepper/pepper_camera_device_host.h"
 #include "content/renderer/pepper/pepper_compositor_host.h"
 #include "content/renderer/pepper/pepper_file_chooser_host.h"
@@ -211,6 +212,9 @@ ContentRendererPepperHostFactory::CreateResourceHost(
       case PpapiHostMsg_AudioInput_Create::ID:
         return base::MakeUnique<PepperAudioInputHost>(host_, instance,
                                                       resource);
+      case PpapiHostMsg_AudioOutput_Create::ID:
+        return base::MakeUnique<PepperAudioOutputHost>(host_, instance,
+                                                       resource);
       case PpapiHostMsg_FileChooser_Create::ID:
         return base::MakeUnique<PepperFileChooserHost>(host_, instance,
                                                        resource);

content/renderer/pepper/pepper_audio_controller.cc

@@ -4,6 +4,7 @@
 
 #include "content/renderer/pepper/pepper_audio_controller.h"
 
+#include "content/renderer/pepper/pepper_audio_output_host.h"
 #include "content/renderer/pepper/pepper_plugin_instance_impl.h"
 #include "content/renderer/pepper/ppb_audio_impl.h"
 #include "content/renderer/render_frame_impl.h"
@@ -27,15 +28,22 @@ void PepperAudioController::AddInstance(PPB_Audio_Impl* audio) {
   if (ppb_audios_.count(audio))
     return;
 
-  if (ppb_audios_.empty()) {
-    RenderFrameImpl* render_frame = instance_->render_frame();
-    if (render_frame)
-      render_frame->PepperStartsPlayback(instance_);
-  }
+  StartPlaybackIfFirstInstance();
 
   ppb_audios_.insert(audio);
 }
 
+void PepperAudioController::AddInstance(PepperAudioOutputHost* audio_output) {
+  if (!instance_)
+    return;
+  if (audio_output_hosts_.count(audio_output))
+    return;
+
+  StartPlaybackIfFirstInstance();
+
+  audio_output_hosts_.insert(audio_output);
+}
+
 void PepperAudioController::RemoveInstance(PPB_Audio_Impl* audio) {
   if (!instance_)
     return;
@@ -44,8 +52,19 @@ void PepperAudioController::RemoveInstance(PPB_Audio_Impl* audio) {
 
   ppb_audios_.erase(audio);
 
-  if (ppb_audios_.empty())
-    NotifyPlaybackStopsOnEmpty();
+  StopPlaybackIfLastInstance();
+}
+
+void PepperAudioController::RemoveInstance(
+    PepperAudioOutputHost* audio_output) {
+  if (!instance_)
+    return;
+  if (!audio_output_hosts_.count(audio_output))
+    return;
+
+  audio_output_hosts_.erase(audio_output);
+
+  StopPlaybackIfLastInstance();
 }
 
 void PepperAudioController::SetVolume(double volume) {
@@ -54,15 +73,19 @@ void PepperAudioController::SetVolume(double volume) {
 
   for (auto* ppb_audio : ppb_audios_)
     ppb_audio->SetVolume(volume);
+
+  for (auto* audio_output_host : audio_output_hosts_)
+    audio_output_host->SetVolume(volume);
 }
 
 void PepperAudioController::OnPepperInstanceDeleted() {
   DCHECK(instance_);
 
-  if (!ppb_audios_.empty())
+  if (!audio_output_hosts_.empty() || !ppb_audios_.empty())
     NotifyPlaybackStopsOnEmpty();
 
   ppb_audios_.clear();
+  audio_output_hosts_.clear();
   instance_ = nullptr;
 }
 
@@ -74,4 +97,21 @@ void PepperAudioController::NotifyPlaybackStopsOnEmpty() {
     render_frame->PepperStopsPlayback(instance_);
 }
 
+void PepperAudioController::StartPlaybackIfFirstInstance() {
+  DCHECK(instance_);
+
+  if (audio_output_hosts_.empty() && ppb_audios_.empty()) {
+    RenderFrameImpl* render_frame = instance_->render_frame();
+    if (render_frame)
+      render_frame->PepperStartsPlayback(instance_);
+  }
+}
+
+void PepperAudioController::StopPlaybackIfLastInstance() {
+  DCHECK(instance_);
+
+  if (audio_output_hosts_.empty() && ppb_audios_.empty())
+    NotifyPlaybackStopsOnEmpty();
+}
+
 }  // namespace content

content/renderer/pepper/pepper_audio_controller.h

@@ -11,6 +11,7 @@
 
 namespace content {
 
+class PepperAudioOutputHost;
 class PepperPluginInstanceImpl;
 class PPB_Audio_Impl;
 
@@ -25,9 +26,11 @@ class PepperAudioController {
 
   // Adds an audio instance to the controller.
   void AddInstance(PPB_Audio_Impl* audio);
+  void AddInstance(PepperAudioOutputHost* audio_output);
 
   // Removes an audio instance from the controller.
   void RemoveInstance(PPB_Audio_Impl* audio);
+  void RemoveInstance(PepperAudioOutputHost* audio_output);
 
   // Sets the volume of all audio instances.
   void SetVolume(double volume);
@@ -42,9 +45,18 @@ class PepperAudioController {
   // only be called when |ppb_audios_| turns from non-empty to empty.
   void NotifyPlaybackStopsOnEmpty();
 
-  // All active audio instances.
+  // Helper functions to deal with the first and last audio instance.
+  void StartPlaybackIfFirstInstance();
+  void StopPlaybackIfLastInstance();
+
+  // All active audio instances that are using the old
+  // PPB_Audio interface.
   std::set<PPB_Audio_Impl*> ppb_audios_;
 
+  // All active audio output instances that are using the new
+  // PPB_AudioOutput interface.
+  std::set<PepperAudioOutputHost*> audio_output_hosts_;
+
   // The Pepper instance which this controller is for. Will be null after
   // OnPepperInstanceDeleted() is called.
   PepperPluginInstanceImpl* instance_;