[Audio Focus] Remove force duck abandon behaviour

If a force duck session abandons audio focus then we
should stop ducking it. It should not have the
custom behaviour.

BUG=931892

Change-Id: Ib6f1198e05179b5bede8cf23414729be0e4b286b
Reviewed-on: https://chromium-review.googlesource.com/c/1481587Reviewed-by: Tommy Steimel <steimel@chromium.org>
Commit-Queue: Becca Hughes <beccahughes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#634371}

services/media_session/audio_focus_manager.cc

@@ -317,7 +317,7 @@ void AudioFocusManager::AbandonAudioFocusInternal(RequestId id) {
     return;
   }
 
-  EnforceAudioFocusAbandon();
+  EnforceAudioFocus();
   MaybeUpdateActiveSession();
 
   // Notify observers that we lost audio focus.
@@ -416,27 +416,6 @@ void AudioFocusManager::RequestAudioFocusInternal(
   std::move(callback).Run();
 }
 
-void AudioFocusManager::EnforceAudioFocusAbandon() {
-  // Allow the top-most MediaSession having force duck to unduck even if
-  // it is not active.
-  if (enforcement_mode_ != mojom::EnforcementMode::kNone) {
-    for (auto iter = audio_focus_stack_.rbegin();
-         iter != audio_focus_stack_.rend(); ++iter) {
-      if (!(*iter)->info()->force_duck)
-        continue;
-
-      // TODO(beccahughes): Replace with std::rotate.
-      auto duck_row = std::move(*iter);
-      duck_row->session()->StopDucking();
-      audio_focus_stack_.erase(std::next(iter).base());
-      audio_focus_stack_.push_back(std::move(duck_row));
-      return;
-    }
-  }
-
-  EnforceAudioFocus();
-}
-
 void AudioFocusManager::EnforceAudioFocus() {
   DCHECK_NE(mojom::EnforcementMode::kDefault, enforcement_mode_);
   if (audio_focus_stack_.empty())

services/media_session/audio_focus_manager.h

@@ -107,7 +107,6 @@ class AudioFocusManager : public mojom::AudioFocusManager,
                                  base::OnceCallback<void()>);
   void AbandonAudioFocusInternal(RequestId);
 
-  void EnforceAudioFocusAbandon();
   void EnforceAudioFocus();
 
   void MaybeUpdateActiveSession();

services/media_session/audio_focus_manager_unittest.cc

@@ -680,8 +680,7 @@ TEST_P(AudioFocusManagerTest, GainDucksForceDuck) {
             GetState(&media_session_1));
 }
 
-TEST_P(AudioFocusManagerTest,
-       AbandoningGainFocusRevokesTopMostForceDuckSession) {
+TEST_P(AudioFocusManagerTest, ForceDuckSessionShouldAlwaysBeDuckedFromGain) {
   test::MockMediaSession media_session_1(true /* force_duck */);
   test::MockMediaSession media_session_2;
   test::MockMediaSession media_session_3;
@@ -702,8 +701,34 @@ TEST_P(AudioFocusManagerTest,
             GetState(&media_session_1));
 
   media_session_3.AbandonAudioFocusFromClient();
-  EXPECT_EQ(IsEnforcementEnabled() ? request_id_1 : request_id_2,
-            GetAudioFocusedSession());
+  EXPECT_EQ(request_id_2, GetAudioFocusedSession());
+  EXPECT_EQ(GetStateFromParam(mojom::MediaSessionInfo::SessionState::kDucking),
+            GetState(&media_session_1));
+
+  media_session_2.AbandonAudioFocusFromClient();
+  EXPECT_EQ(request_id_1, GetAudioFocusedSession());
+  EXPECT_EQ(mojom::MediaSessionInfo::SessionState::kActive,
+            GetState(&media_session_1));
+}
+
+TEST_P(AudioFocusManagerTest,
+       ForceDuckSessionShouldAlwaysBeDuckedFromTransient) {
+  test::MockMediaSession media_session_1(true /* force_duck */);
+  test::MockMediaSession media_session_2;
+
+  AudioFocusManager::RequestId request_id_1 =
+      RequestAudioFocus(&media_session_1, mojom::AudioFocusType::kGain);
+  RequestAudioFocus(&media_session_2, mojom::AudioFocusType::kGainTransient);
+
+  EXPECT_EQ(mojom::MediaSessionInfo::SessionState::kActive,
+            GetState(&media_session_2));
+  EXPECT_EQ(GetStateFromParam(mojom::MediaSessionInfo::SessionState::kDucking),
+            GetState(&media_session_1));
+
+  media_session_2.AbandonAudioFocusFromClient();
+  EXPECT_EQ(request_id_1, GetAudioFocusedSession());
+  EXPECT_EQ(mojom::MediaSessionInfo::SessionState::kActive,
+            GetState(&media_session_1));
 }
 
 TEST_P(AudioFocusManagerTest, AudioFocusObserver_RequestNoop) {