Expose flash playback status and volume control to content renderer

content/renderer/pepper/pepper_audio_control_delegate.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_control_delegate.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 {
+
+PepperAudioControlDelegate::PepperAudioControlDelegate(
+    PepperPluginInstanceImpl* pepper_instance)
+    : pepper_instance_(pepper_instance) {
+  DCHECK(pepper_instance_);
+}
+
+PepperAudioControlDelegate::~PepperAudioControlDelegate() {
+  DCHECK(!pepper_instance_);

[bbudge, 2016/06/22 18:14:55]

It seems to me like you could instead:

if (instance_)
  OnPepperInstanceDeleted();

[Zhiqiang Zhang (Slow), 2016/06/22 21:00:42]

Done.

+}
+
+void PepperAudioControlDelegate::AddActiveAudioInstance(PPB_Audio_Impl* audio) {
+  if (!pepper_instance_) return;
+  if (ppb_audios_.count(audio)) return;

[bbudge, 2016/06/22 18:14:54]

It might be better to DCHECK that the instance isn't already in the set. Is
there a reason to silently do nothing?

[Zhiqiang Zhang (Slow), 2016/06/22 21:00:42]

The StartPlayback signal originates from Pepper. I think we shouldn't trust it
not calling two consequtive starts (or stops)?
WDYT?

+
+  if (ppb_audios_.empty()) {
+    RenderFrameImpl* render_frame = pepper_instance_->render_frame();
+    if (render_frame)
+      render_frame->PepperStartsPlayback(pepper_instance_);
+  }
+
+  ppb_audios_.insert(audio);
+}
+
+void PepperAudioControlDelegate::RemoveActiveAudioInstance(
+    PPB_Audio_Impl* audio) {
+  if (!pepper_instance_) return;
+  if (!ppb_audios_.count(audio)) return;

[bbudge, 2016/06/22 18:14:54]

DCHECK?

[Zhiqiang Zhang (Slow), 2016/06/22 21:00:42]

Ditto.

+
+  ppb_audios_.erase(audio);
+
+  if (ppb_audios_.empty()) {
+    RenderFrameImpl* render_frame = pepper_instance_->render_frame();
+    if (render_frame)
+      render_frame->PepperStopsPlayback(pepper_instance_);
+  }
+}
+
+void PepperAudioControlDelegate::SetVolume(double volume) {
+  if (!pepper_instance_) return;
+
+  for (auto* ppb_audio : ppb_audios_)
+    ppb_audio->SetVolume(volume);
+}
+
+void PepperAudioControlDelegate::OnPepperInstanceDeleted() {
+  DCHECK(!pepper_instance_);

[bbudge, 2016/06/22 18:14:54]

DCHECK(instance_);

[Zhiqiang Zhang (Slow), 2016/06/22 21:00:42]

Done.

+
+  if (!ppb_audios_.empty()) {
+    RenderFrameImpl* render_frame = pepper_instance_->render_frame();
+    if (render_frame)
+      render_frame->PepperStopsPlayback(pepper_instance_);
+  }

[bbudge, 2016/06/22 18:14:54]

This duplicated code could be moved to a private helper method: e.g.
StopPlaybackOnEmpty. The code here could then clear the audio set, then call the
method, then set instance_ to null.

[Zhiqiang Zhang (Slow), 2016/06/22 21:00:42]

Done.

+
+  ppb_audios_.clear();
+  pepper_instance_ = nullptr;
+}
+
+}