Let Flash take one-shot focus in default MediaSession

content/browser/media/session/pepper_player_delegate.cc

Index: content/browser/media/session/pepper_player_delegate.cc
diff --git a/content/browser/media/session/pepper_player_delegate.cc b/content/browser/media/session/pepper_player_delegate.cc
index 8c38b2a57e54a32fc307284344ae7e1a93661a6b..7b95734faa6b4ac566c07915eb635076c4e5f221 100644
--- a/content/browser/media/session/pepper_player_delegate.cc
+++ b/content/browser/media/session/pepper_player_delegate.cc
@@ -8,6 +8,7 @@
 #include "content/browser/media/session/pepper_playback_observer.h"
 #include "content/browser/web_contents/web_contents_impl.h"
 #include "content/common/frame_messages.h"
+#include "media/base/media_switches.h"
 
 namespace content {
 
@@ -15,6 +16,12 @@ namespace {
 
 const double kDuckVolume = 0.2f;
 
+bool ShouldDuckFlash() {
+  return base::CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
+             switches::kEnableDefaultMediaSession) ==
+         switches::kEnableDefaultMediaSessionDuckFlash;
+}
+
 }  // anonymous namespace
 
 const int PepperPlayerDelegate::kPlayerId = 0;
@@ -27,18 +34,27 @@ PepperPlayerDelegate::PepperPlayerDelegate(
 PepperPlayerDelegate::~PepperPlayerDelegate() = default;
 
 void PepperPlayerDelegate::OnSuspend(int player_id) {
+  if (!ShouldDuckFlash())
+    return;
+
   // 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) {
+  if (!ShouldDuckFlash())
+    return;
+
   DCHECK_EQ(player_id, kPlayerId);
   SetVolume(player_id, 1.0f);
 }
 
 void PepperPlayerDelegate::OnSetVolumeMultiplier(int player_id,
                                                  double volume_multiplier) {
+  if (!ShouldDuckFlash())
+    return;
+
   DCHECK_EQ(player_id, kPlayerId);
   SetVolume(player_id, volume_multiplier);
 }