Expose flash playback status and volume control to content renderer

content/renderer/pepper/pepper_audio_controller.cc

+// Copyright 2016 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 "content/renderer/pepper/pepper_audio_controller.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"
+
+namespace content {
+
+PepperAudioController::PepperAudioController(
+    PepperPluginInstanceImpl* instance)
+    : instance_(instance) {
+  DCHECK(instance_);
+}
+
+PepperAudioController::~PepperAudioController() {
+  if (instance_)
+    OnPepperInstanceDeleted();
+}
+
+void PepperAudioController::AddInstance(PPB_Audio_Impl* audio) {
+  if (!instance_)
+    return;
+  if (ppb_audios_.count(audio))

[dcheng, 2016/06/23 19:35:36]

Why do we have to verify this here and below? Why would something get added
twice in a row or removed twice in a row?

+    return;
+
+  if (ppb_audios_.empty()) {
+    RenderFrameImpl* render_frame = instance_->render_frame();
+    if (render_frame)
+      render_frame->PepperStartsPlayback(instance_);
+  }
+
+  ppb_audios_.insert(audio);
+}
+
+void PepperAudioController::RemoveInstance(PPB_Audio_Impl* audio) {
+  if (!instance_)
+    return;
+  if (!ppb_audios_.count(audio))
+    return;
+
+  ppb_audios_.erase(audio);
+
+  if (ppb_audios_.empty())
+    NotifyPlaybackStopsOnEmpty();
+}
+
+void PepperAudioController::SetVolume(double volume) {
+  if (!instance_)
+    return;
+
+  for (auto* ppb_audio : ppb_audios_)
+    ppb_audio->SetVolume(volume);
+}
+
+void PepperAudioController::OnPepperInstanceDeleted() {
+  DCHECK(instance_);
+
+  if (!ppb_audios_.empty())
+    NotifyPlaybackStopsOnEmpty();
+
+  ppb_audios_.clear();
+  instance_ = nullptr;
+}
+
+void PepperAudioController::NotifyPlaybackStopsOnEmpty() {
+  DCHECK(instance_);
+
+  RenderFrameImpl* render_frame = instance_->render_frame();
+  if (render_frame)
+    render_frame->PepperStopsPlayback(instance_);
+}
+
+}  // namespace content