[Autoplay] Add audio context feature

Add a feature to disable AudioContext playbacks counting
towards the MEI score.

BUG=878460

Change-Id: I486f3853ebc26a703e52712bee13600c99c7be14
Reviewed-on: https://chromium-review.googlesource.com/1204728Reviewed-by: Mounir Lamouri <mlamouri@chromium.org>
Commit-Queue: Becca Hughes <beccahughes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#589046}

chrome/browser/media/media_engagement_contents_observer.cc

@@ -529,6 +529,9 @@ void MediaEngagementContentsObserver::UpdatePageTimer() {
 }
 
 bool MediaEngagementContentsObserver::AreAudioContextConditionsMet() const {
+  if (!base::FeatureList::IsEnabled(media::kRecordWebAudioEngagement))
+    return false;
+
   if (audio_context_players_.empty())
     return false;
 

chrome/browser/media/media_engagement_contents_observer_unittest.cc

@@ -28,6 +28,7 @@
 #include "content/public/browser/web_contents.h"
 #include "content/public/test/test_service_manager_context.h"
 #include "content/public/test/web_contents_tester.h"
+#include "media/base/media_switches.h"
 #include "services/metrics/public/cpp/ukm_builders.h"
 #include "services/metrics/public/cpp/ukm_source.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ -39,9 +40,6 @@ class MediaEngagementContentsObserverTest
       : task_runner_(new base::TestMockTimeTaskRunner()) {}
 
   void SetUp() override {
-    scoped_feature_list_.InitFromCommandLine("RecordMediaEngagementScores",
-                                             std::string());
-
     ChromeRenderViewHostTestHarness::SetUp();
 
     test_service_manager_context_ =
@@ -449,8 +447,6 @@ class MediaEngagementContentsObserverTest
 
   std::unique_ptr<MediaEngagementService> service_;
 
-  base::test::ScopedFeatureList scoped_feature_list_;
-
   ukm::TestAutoSetUkmRecorder test_ukm_recorder_;
 
   base::HistogramTester histogram_tester_;
@@ -1373,3 +1369,19 @@ TEST_F(MediaEngagementContentsObserverTest, GetOrCreateSession_WithOpener) {
   EXPECT_EQ(GetSessionFor(other_observer),
             GetOrCreateSession(url::Origin::Create(url), opener.get()));
 }
+
+TEST_F(MediaEngagementContentsObserverTest, IgnoreAudioContextIfDisabled) {
+  base::test::ScopedFeatureList feature_list;
+  feature_list.InitAndDisableFeature(media::kRecordWebAudioEngagement);
+
+  Navigate(GURL("https://www.example.com"));
+  SimulateAudioContextStarted(0);
+  SimulateAudible();
+
+  EXPECT_FALSE(AreAudioContextConditionsMet());
+  EXPECT_FALSE(IsAudioContextTimerRunning());
+  EXPECT_FALSE(WasSignificantAudioContextPlaybackRecorded());
+
+  SimulateAudioContextPlaybackTimerFired();
+  EXPECT_FALSE(WasSignificantAudioContextPlaybackRecorded());
+}

media/base/media_switches.cc

@@ -429,6 +429,10 @@ const base::Feature kUseModernMediaControls{"UseModernMediaControls",
 const base::Feature kRecordMediaEngagementScores{
     "RecordMediaEngagementScores", base::FEATURE_ENABLED_BY_DEFAULT};
 
+// Enables Media Engagement Index recording for Web Audio playbacks.
+const base::Feature kRecordWebAudioEngagement{"RecordWebAudioEngagement",
+                                              base::FEATURE_ENABLED_BY_DEFAULT};
+
 // The following Media Engagement flags are not enabled on mobile platforms:
 // - MediaEngagementBypassAutoplayPolicies: enables the Media Engagement Index
 //   data to be esude to override autoplay policies. An origin with a high MEI

media/base/media_switches.h

@@ -109,6 +109,7 @@ MEDIA_EXPORT extern const base::Feature kHardwareSecureDecryption;
 MEDIA_EXPORT extern const base::Feature kLowDelayVideoRenderingOnLiveStream;
 MEDIA_EXPORT extern const base::Feature kMediaCastOverlayButton;
 MEDIA_EXPORT extern const base::Feature kRecordMediaEngagementScores;
+MEDIA_EXPORT extern const base::Feature kRecordWebAudioEngagement;
 MEDIA_EXPORT extern const base::Feature kMediaEngagementBypassAutoplayPolicies;
 MEDIA_EXPORT extern const base::Feature kMemoryPressureBasedSourceBufferGC;
 MEDIA_EXPORT extern const base::Feature kMojoVideoDecoder;