[Blink>Media] Moving autoplay logic to AutoplayPolicy

third_party/WebKit/Source/core/html/media/AutoplayPolicy.cpp

+// Copyright 2017 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 "core/html/media/AutoplayPolicy.h"
+
+#include "core/dom/Document.h"
+#include "core/dom/ElementVisibilityObserver.h"
+#include "core/frame/ContentSettingsClient.h"
+#include "core/frame/LocalFrame.h"
+#include "core/frame/Settings.h"
+#include "core/html/HTMLMediaElement.h"
+#include "core/html/media/AutoplayUmaHelper.h"
+#include "platform/RuntimeEnabledFeatures.h"
+#include "platform/UserGestureIndicator.h"
+#include "public/platform/WebMediaPlayer.h"
+
+namespace blink {
+
+namespace {
+
+bool IsDocumentCrossOrigin(Document& document) {
+  const LocalFrame* frame = document.GetFrame();
+  return frame && frame->IsCrossOriginSubframe();
+}
+
+// Returns whether |document| is whitelisted for autoplay. If true, the user
+// gesture lock will be initilized as false, indicating that the element is
+// allowed to autoplay unmuted without user gesture.
+bool IsDocumentWhitelisted(Document& document) {
+  DCHECK(document.GetSettings());
+
+  const String& whitelist_scope =
+      document.GetSettings()->GetMediaPlaybackGestureWhitelistScope();
+  if (whitelist_scope.IsNull() || whitelist_scope.IsEmpty())
+    return false;
+
+  return document.Url().GetString().StartsWith(whitelist_scope);
+}
+
+// Return true if and only if the document settings specifies media playback
+// requires user gesture.
+bool ComputeLockedPendingUserGesture(Document& document) {
+  if (!document.GetSettings())
+    return false;
+
+  if (IsDocumentWhitelisted(document)) {
+    return false;
+  }
+
+  if (document.GetSettings()
+          ->GetCrossOriginMediaPlaybackRequiresUserGesture() &&
+      IsDocumentCrossOrigin(document)) {
+    return true;
+  }
+
+  return document.GetSettings()->GetMediaPlaybackRequiresUserGesture();
+}
+
+}  // anonymous namespace
+
+AutoplayPolicy::AutoplayPolicy(HTMLMediaElement* element)
+    : locked_pending_user_gesture_(false),
+      locked_pending_user_gesture_if_cross_origin_experiment_enabled_(true),
+      element_(element),
+      autoplay_visibility_observer_(nullptr),
+      autoplay_uma_helper_(AutoplayUmaHelper::Create(element)) {
+  locked_pending_user_gesture_ =
+      ComputeLockedPendingUserGesture(element->GetDocument());
+  locked_pending_user_gesture_if_cross_origin_experiment_enabled_ =
+      IsDocumentCrossOrigin(element->GetDocument());
+}
+
+void AutoplayPolicy::VideoWillBeDrawnToCanvas() const {
+  autoplay_uma_helper_->VideoWillBeDrawnToCanvas();
+}
+
+void AutoplayPolicy::DidMoveToNewDocument(Document& old_document) {
+  // If any experiment is enabled, then we want to enable a user gesture by
+  // default, otherwise the experiment does nothing.
+  bool old_document_requires_user_gesture =
+      ComputeLockedPendingUserGesture(old_document);
+  bool new_document_requires_user_gesture =
+      ComputeLockedPendingUserGesture(element_->GetDocument());
+  if (new_document_requires_user_gesture && !old_document_requires_user_gesture)
+    locked_pending_user_gesture_ = true;
+
+  if (IsDocumentCrossOrigin(element_->GetDocument()) &&
+      !IsDocumentCrossOrigin(old_document))
+    locked_pending_user_gesture_if_cross_origin_experiment_enabled_ = true;
+
+  autoplay_uma_helper_->DidMoveToNewDocument(old_document);
+}
+
+bool AutoplayPolicy::IsEligibleForAutoplayMuted() const {
+  return element_->IsHTMLVideoElement() && element_->muted() &&
+         RuntimeEnabledFeatures::autoplayMutedVideosEnabled();
+}
+
+void AutoplayPolicy::StartAutoplayMutedWhenVisible() {
+  // We might end up in a situation where the previous
+  // observer didn't had time to fire yet. We can avoid
+  // creating a new one in this case.
+  if (autoplay_visibility_observer_)
+    return;
+
+  autoplay_visibility_observer_ = new ElementVisibilityObserver(
+      element_, WTF::Bind(&AutoplayPolicy::OnVisibilityChangedForAutoplay,
+                          WrapWeakPersistent(this)));
+  autoplay_visibility_observer_->Start();
+}
+
+void AutoplayPolicy::StopAutoplayMutedWhenVisible() {
+  if (!autoplay_visibility_observer_)
+    return;
+
+  autoplay_visibility_observer_->Stop();
+  autoplay_visibility_observer_ = nullptr;
+}
+
+bool AutoplayPolicy::RequestAutoplayUnmute() {
+  bool was_autoplaying_muted = IsAutoplayingMuted();

[Zhiqiang Zhang (Slow), 2017/04/20 15:36:26]

I found why the tests are broken...

Actually the muted attribute throughout this method is always true, as it is
called before the muted attribute is set to new value. Then
IsGestureNeededForPlayback() will return false because the muted attribute is
true.

PTAL the new code which fixed the issue.

BTW, I'm a bit surprised I didn't see this in my local debug build, because the
pause event will be sent out anyway when the media finishes. I assume the test
timeout is longer than the media duration. Maybe we should increase the test
file duration.

+
+  TryUnlockingUserGesture();
+
+  if (was_autoplaying_muted) {
+    if (IsGestureNeededForPlayback()) {
+      autoplay_uma_helper_->RecordAutoplayUnmuteStatus(
+          AutoplayUnmuteActionStatus::kFailure);
+      return false;
+    }
+    autoplay_uma_helper_->RecordAutoplayUnmuteStatus(
+        AutoplayUnmuteActionStatus::kSuccess);
+  }
+  return true;
+}
+
+bool AutoplayPolicy::RequestAutoplayByAttribute() {
+  if (!ShouldAutoplay())
+    return false;
+
+  autoplay_uma_helper_->OnAutoplayInitiated(AutoplaySource::kAttribute);
+
+  if (IsGestureNeededForPlayback()) {
+    autoplay_uma_helper_->RecordCrossOriginAutoplayResult(
+        CrossOriginAutoplayResult::kAutoplayBlocked);
+    return false;
+  }
+
+  if (IsGestureNeededForPlaybackIfCrossOriginExperimentEnabled()) {
+    autoplay_uma_helper_->RecordCrossOriginAutoplayResult(
+        CrossOriginAutoplayResult::kAutoplayBlocked);
+  } else {
+    autoplay_uma_helper_->RecordCrossOriginAutoplayResult(
+        CrossOriginAutoplayResult::kAutoplayAllowed);
+  }
+
+  if (!IsEligibleForAutoplayMuted())

[mlamouri (slow - plz ping), 2017/04/20 14:37:27]

Maybe add a comment reminding the user that this only makes sense because of the
`!IsGestureNeddedForPlayback` above?

[Zhiqiang Zhang (Slow), 2017/04/20 15:36:26]

Done.

+    return true;
+
+  // Autoplay muted video should be handled by AutoplayPolicy based on the
+  // visibily.
+  StartAutoplayMutedWhenVisible();
+  return false;
+}
+
+Nullable<ExceptionCode> AutoplayPolicy::RequestPlay() {
+  if (!UserGestureIndicator::ProcessingUserGesture()) {
+    autoplay_uma_helper_->OnAutoplayInitiated(AutoplaySource::kMethod);
+    if (IsGestureNeededForPlayback()) {
+      autoplay_uma_helper_->RecordCrossOriginAutoplayResult(
+          CrossOriginAutoplayResult::kAutoplayBlocked);
+      return kNotAllowedError;
+    }
+
+    if (IsGestureNeededForPlaybackIfCrossOriginExperimentEnabled()) {
+      autoplay_uma_helper_->RecordCrossOriginAutoplayResult(
+          CrossOriginAutoplayResult::kAutoplayBlocked);
+    } else {
+      autoplay_uma_helper_->RecordCrossOriginAutoplayResult(
+          CrossOriginAutoplayResult::kAutoplayAllowed);
+    }
+  } else {
+    autoplay_uma_helper_->RecordCrossOriginAutoplayResult(
+        CrossOriginAutoplayResult::kPlayedWithGesture);
+    TryUnlockingUserGesture();
+  }
+
+  return nullptr;
+}
+
+bool AutoplayPolicy::IsAutoplayingMuted() const {
+  if (!element_->IsHTMLVideoElement() ||
+      !RuntimeEnabledFeatures::autoplayMutedVideosEnabled()) {
+    return false;
+  }
+
+  return !element_->paused() && element_->muted() &&
+         IsLockedPendingUserGesture();
+}
+
+bool AutoplayPolicy::IsLockedPendingUserGesture() const {
+  return locked_pending_user_gesture_;
+}
+
+void AutoplayPolicy::TryUnlockingUserGesture() {
+  if (IsLockedPendingUserGesture() &&
+      UserGestureIndicator::UtilizeUserGesture()) {
+    UnlockUserGesture();
+  }
+}
+
+void AutoplayPolicy::UnlockUserGesture() {
+  locked_pending_user_gesture_ = false;
+  locked_pending_user_gesture_if_cross_origin_experiment_enabled_ = false;
+}
+
+bool AutoplayPolicy::IsGestureNeededForPlayback() const {
+  if (!locked_pending_user_gesture_)
+    return false;
+
+  return IsGestureNeededForPlaybackIfPendingUserGestureIsLocked();
+}
+
+bool AutoplayPolicy::IsGestureNeededForPlaybackIfPendingUserGestureIsLocked()
+    const {
+  if (element_->GetLoadType() == WebMediaPlayer::kLoadTypeMediaStream)
+    return false;
+
+  // We want to allow muted video to autoplay if:
+  // - the flag is enabled;
+  // - Data Saver is not enabled;
+  // - Preload was not disabled (low end devices);
+  // - Autoplay is enabled in settings;
+  if (element_->IsHTMLVideoElement() && element_->muted() &&
+      RuntimeEnabledFeatures::autoplayMutedVideosEnabled() &&
+      !(element_->GetDocument().GetSettings() &&
+        element_->GetDocument().GetSettings()->GetDataSaverEnabled()) &&
+      !(element_->GetDocument().GetSettings() &&
+        element_->GetDocument()
+            .GetSettings()
+            ->GetForcePreloadNoneForMediaElements()) &&
+      IsAutoplayAllowedPerSettings()) {
+    return false;
+  }
+
+  return true;
+}
+
+void AutoplayPolicy::OnVisibilityChangedForAutoplay(bool is_visible) {
+  if (!is_visible) {
+    if (element_->can_autoplay_ && element_->Autoplay()) {
+      element_->PauseInternal();
+      element_->can_autoplay_ = true;
+    }
+    return;
+  }
+
+  if (ShouldAutoplay()) {
+    element_->paused_ = false;
+    element_->ScheduleEvent(EventTypeNames::play);
+    element_->ScheduleNotifyPlaying();
+
+    element_->UpdatePlayState();
+  }
+}
+
+bool AutoplayPolicy::IsGestureNeededForPlaybackIfCrossOriginExperimentEnabled()
+    const {
+  if (!locked_pending_user_gesture_if_cross_origin_experiment_enabled_)
+    return false;
+
+  return IsGestureNeededForPlaybackIfPendingUserGestureIsLocked();
+}
+
+bool AutoplayPolicy::IsAutoplayAllowedPerSettings() const {
+  LocalFrame* frame = element_->GetDocument().GetFrame();
+  if (!frame)
+    return false;
+  return frame->GetContentSettingsClient()->AllowAutoplay(true);
+}
+
+bool AutoplayPolicy::ShouldAutoplay() {
+  if (element_->GetDocument().IsSandboxed(kSandboxAutomaticFeatures))
+    return false;
+  return element_->can_autoplay_ && element_->paused_ && element_->Autoplay();
+}
+
+DEFINE_TRACE(AutoplayPolicy) {
+  visitor->Trace(element_);
+  visitor->Trace(autoplay_visibility_observer_);
+  visitor->Trace(autoplay_uma_helper_);
+}
+
+}  // namespace blink