Let Flash join and be controlled by media session

content/browser/media/session/pepper_player_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/browser/media/session/pepper_player_delegate.h"
+
+#include "content/browser/frame_host/render_frame_host_impl.h"
+#include "content/browser/media/session/pepper_playback_observer.h"
+#include "content/browser/web_contents/web_contents_impl.h"
+#include "content/common/frame_messages.h"
+
+namespace content {
+
+namespace {
+const double kDuckVolume = 0.2f;
+const int kPlayerId = 0;

[dcheng, 2016/07/01 05:57:59]

Note: this is fine, but my comment was directed mostly at the
pepper_playback_observer.cc. When calling a function, the context for an
argument that's just '0' isn't so clear. Whereas in this file, it's always
compared to a variable named player_id, so it's more obvious from the context

[Zhiqiang Zhang (Slow), 2016/07/01 11:01:07]

OK, now I moved all the Ids in one place (pepper_player_delegate.h), so I think
it will be more consistent.

+}  // anonymous namespace
+
+PepperPlayerDelegate::PepperPlayerDelegate(
+    WebContentsImpl* contents, int32_t pp_instance)
+    : contents_(contents),
+      pp_instance_(pp_instance) {}
+
+PepperPlayerDelegate::~PepperPlayerDelegate() = default;
+
+void PepperPlayerDelegate::OnSuspend(int player_id) {
+  // Pepper player cannot be really suspended. Duck the volume instead.
+  DCHECK_EQ(player_id, kPlayerId);
+  SetVolume(player_id, kDuckVolume);
+}
+
+void PepperPlayerDelegate::OnResume(int player_id) {
+  DCHECK_EQ(player_id, kPlayerId);
+  SetVolume(player_id, 1.0f);
+}
+
+void PepperPlayerDelegate::OnSetVolumeMultiplier(int player_id,
+                                                 double volume_multiplier) {
+  DCHECK_EQ(player_id, kPlayerId);
+  SetVolume(player_id, volume_multiplier);
+}
+
+void PepperPlayerDelegate::SetVolume(int player_id, double volume) {
+  contents_->Send(new FrameMsg_SetPepperVolume(
+      contents_->GetMainFrame()->routing_id(), pp_instance_, volume));
+}
+
+}  // namespace content