Reland "Media Controls: allow navigation with accessibility tools."

This is a reland of a5439425

The CL failed after CQ because another CL that landed a couple of
commits prior broke some assumptions made in the unit tests.

Original change's description:
> Media Controls: allow navigation with accessibility tools.
>
> The media controls auto-hide mechanism breaks accessibility tools. This
> prevents the controls from fully hiding when navigated with
> accessibility tools. Instead of marking themselves as `display:none;`,
> this only mark the controls as hidden and will show them again if the
> user navigates trough them again. Similar to using a mouse.
>
> Bug: 667833
> Change-Id: I7c2dbfd4b047e2955f6ffa9fb1a5f3bbe37878fd
> Reviewed-on: https://chromium-review.googlesource.com/999637
> Reviewed-by: Tommy Steimel <steimel@chromium.org>
> Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
> Commit-Queue: Mounir Lamouri <mlamouri@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#549774}

TBR=dmazzoni@chromium.org, pfeldman@chromium.org

Bug: 667833
Change-Id: I03bbe4858d456a9131b257ca709f7d8728e712f7
Reviewed-on: https://chromium-review.googlesource.com/1007075Reviewed-by: Mounir Lamouri <mlamouri@chromium.org>
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Commit-Queue: Mounir Lamouri <mlamouri@chromium.org>
Cr-Commit-Position: refs/heads/master@{#550096}

third_party/blink/renderer/modules/accessibility/ax_media_controls.cc

@@ -105,6 +105,23 @@ MediaControlElementType AccessibilityMediaControl::ControlType() const {
       GetLayoutObject()->GetNode());
 }
 
+bool AccessibilityMediaControl::OnNativeScrollToGlobalPointAction(
+    const IntPoint& point) const {
+  MediaControlElementsHelper::NotifyMediaControlAccessibleFocus(GetElement());
+  return AXLayoutObject::OnNativeScrollToGlobalPointAction(point);
+}
+
+bool AccessibilityMediaControl::OnNativeScrollToMakeVisibleAction() const {
+  MediaControlElementsHelper::NotifyMediaControlAccessibleFocus(GetElement());
+  return AXLayoutObject::OnNativeScrollToMakeVisibleAction();
+}
+
+bool AccessibilityMediaControl::OnNativeScrollToMakeVisibleWithSubFocusAction(
+    const IntRect& rect) const {
+  MediaControlElementsHelper::NotifyMediaControlAccessibleFocus(GetElement());
+  return AXLayoutObject::OnNativeScrollToMakeVisibleWithSubFocusAction(rect);
+}
+
 String AccessibilityMediaControl::TextAlternative(
     bool recursive,
     bool in_aria_labelled_by_traversal,

third_party/blink/renderer/modules/accessibility/ax_media_controls.h

@@ -54,6 +54,11 @@ class AccessibilityMediaControl : public AXLayoutObject {
                      AXDescriptionFrom&,
                      AXObjectVector* description_objects) const override;
 
+  bool OnNativeScrollToGlobalPointAction(const IntPoint&) const override;
+  bool OnNativeScrollToMakeVisibleAction() const override;
+  bool OnNativeScrollToMakeVisibleWithSubFocusAction(
+      const IntRect&) const override;
+
  protected:
   AccessibilityMediaControl(LayoutObject*, AXObjectCacheImpl&);
   MediaControlElementType ControlType() const;

third_party/blink/renderer/modules/media_controls/elements/media_control_elements_helper.cc

@@ -12,6 +12,7 @@
 #include "third_party/blink/renderer/core/layout/layout_view.h"
 #include "third_party/blink/renderer/modules/media_controls/elements/media_control_div_element.h"
 #include "third_party/blink/renderer/modules/media_controls/elements/media_control_input_element.h"
+#include "third_party/blink/renderer/modules/media_controls/media_controls_impl.h"
 
 namespace blink {
 
@@ -116,4 +117,15 @@ HTMLDivElement* MediaControlElementsHelper::CreateDivWithId(
   return element;
 }
 
+// static
+void MediaControlElementsHelper::NotifyMediaControlAccessibleFocus(
+    Element* element) {
+  const HTMLMediaElement* media_element = ToParentMediaElement(element);
+  if (!media_element || !media_element->GetMediaControls())
+    return;
+
+  static_cast<MediaControlsImpl*>(media_element->GetMediaControls())
+      ->OnAccessibleFocus();
+}
+
 }  // namespace blink

third_party/blink/renderer/modules/media_controls/elements/media_control_elements_helper.h

@@ -60,6 +60,10 @@ class MediaControlElementsHelper final {
   // element ID.
   static HTMLDivElement* CreateDivWithId(const WTF::AtomicString& id,
                                          ContainerNode* parent);
+
+  // Utility function that notifies the media controls in which the element is
+  // that it was focused by an accessibility tool.
+  static void NotifyMediaControlAccessibleFocus(Element*);
 };
 
 }  // namespace blink

third_party/blink/renderer/modules/media_controls/elements/media_control_panel_element.cc

@@ -68,6 +68,10 @@ void MediaControlPanelElement::MakeTransparent() {
   StartTimer();
 }
 
+void MediaControlPanelElement::SetKeepDisplayedForAccessibility(bool value) {
+  keep_displayed_for_accessibility_ = value;
+}
+
 void MediaControlPanelElement::DefaultEventHandler(Event* event) {
   // Suppress the media element activation behavior (toggle play/pause) when
   // any part of the control panel is clicked.
@@ -97,7 +101,7 @@ void MediaControlPanelElement::StopTimer() {
 }
 
 void MediaControlPanelElement::TransitionTimerFired(TimerBase*) {
-  if (!opaque_)
+  if (!opaque_ && !keep_displayed_for_accessibility_)
     SetIsWanted(false);
 
   StopTimer();

third_party/blink/renderer/modules/media_controls/elements/media_control_panel_element.h

@@ -25,6 +25,8 @@ class MediaControlPanelElement final : public MediaControlDivElement {
   void MakeOpaque();
   void MakeTransparent();
 
+  void SetKeepDisplayedForAccessibility(bool);
+
  private:
   void DefaultEventHandler(Event*) override;
   bool KeepEventInNode(Event*) override;
@@ -36,6 +38,7 @@ class MediaControlPanelElement final : public MediaControlDivElement {
 
   bool is_displayed_ = false;
   bool opaque_ = true;
+  bool keep_displayed_for_accessibility_ = false;
 
   TaskRunnerTimer<MediaControlPanelElement> transition_timer_;
 };

third_party/blink/renderer/modules/media_controls/media_controls_impl.cc

@@ -1267,6 +1267,17 @@ void MediaControlsImpl::MaybeToggleControlsFromTap() {
   }
 }
 
+void MediaControlsImpl::OnAccessibleFocus() {
+  panel_->SetKeepDisplayedForAccessibility(true);
+
+  if (!MediaElement().ShouldShowControls())
+    return;
+
+  keep_showing_until_timer_fires_ = true;
+  StartHideMediaControlsTimer();
+  MaybeShow();
+}
+
 void MediaControlsImpl::DefaultEventHandler(Event* event) {
   HTMLDivElement::DefaultEventHandler(event);
 
@@ -1295,15 +1306,17 @@ void MediaControlsImpl::DefaultEventHandler(Event* event) {
   if ((event->type() == EventTypeNames::pointerover ||
        event->type() == EventTypeNames::pointermove ||
        event->type() == EventTypeNames::pointerout) &&
-      !is_touch_interaction_)
+      !is_touch_interaction_) {
     HandlePointerEvent(event);
+  }
 
   // If the user is interacting with the controls via the keyboard, don't hide
   // the controls. This will fire when the user tabs between controls (focusin)
   // or when they seek either the timeline or volume sliders (input).
   if (event->type() == EventTypeNames::focusin ||
-      event->type() == EventTypeNames::input)
+      event->type() == EventTypeNames::input) {
     ResetHideMediaControlsTimer();
+  }
 
   if (event->IsKeyboardEvent() &&
       !IsSpatialNavigationEnabled(GetDocument().GetFrame())) {

third_party/blink/renderer/modules/media_controls/media_controls_impl.h

@@ -185,6 +185,11 @@ class MODULES_EXPORT MediaControlsImpl final : public HTMLDivElement,
 
   void MaybeToggleControlsFromTap();
 
+  // Called by accessibility code to notify that the controls was focused by an
+  // accessibility tool. This is meant to be replaced by AOM when the event will
+  // be exposed to the platform.
+  void OnAccessibleFocus();
+
  private:
   // MediaControlsMediaEventListener is a component that is listening to events
   // and calling the appropriate callback on MediaControlsImpl. The object is

third_party/blink/renderer/modules/media_controls/media_controls_impl_test.cc

@@ -138,7 +138,7 @@ bool IsElementVisible(Element& element) {
   const CSSPropertyValueSet* inline_style = element.InlineStyle();
 
   if (!inline_style)
-    return true;
+    return element.getAttribute("class") != "transparent";
 
   if (inline_style->GetPropertyValue(CSSPropertyDisplay) == "none")
     return false;
@@ -1068,6 +1068,52 @@ TEST_F(MediaControlsImplTestWithMockScheduler, CursorHidesWhenControlsHide) {
   EXPECT_TRUE(IsCursorHidden());
 }
 
+TEST_F(MediaControlsImplTestWithMockScheduler, AccessibleFocusShowsControls) {
+  EnsureSizing();
+
+  Element* panel = MediaControls().PanelElement();
+
+  MediaControls().MediaElement().SetSrc("http://example.com");
+  MediaControls().MediaElement().Play();
+
+  platform_->RunForPeriodSeconds(2);
+  EXPECT_TRUE(IsElementVisible(*panel));
+
+  MediaControls().OnAccessibleFocus();
+  platform_->RunForPeriodSeconds(2);
+  EXPECT_TRUE(IsElementVisible(*panel));
+
+  platform_->RunForPeriodSeconds(2);
+  EXPECT_FALSE(IsElementVisible(*panel));
+
+  MediaControls().OnAccessibleFocus();
+  platform_->RunForPeriodSeconds(2);
+  EXPECT_TRUE(IsElementVisible(*panel));
+}
+
+TEST_F(MediaControlsImplTestWithMockScheduler,
+       AccessibleFocusKeepsControlsHiddenButDisplayed) {
+  EnsureSizing();
+
+  Element* panel = MediaControls().PanelElement();
+
+  MediaControls().MediaElement().SetSrc("http://example.com");
+  MediaControls().MediaElement().Play();
+
+  platform_->RunForPeriodSeconds(2);
+  EXPECT_TRUE(IsElementVisible(*panel));
+
+  MediaControls().OnAccessibleFocus();
+  platform_->RunForPeriodSeconds(4);
+  EXPECT_FALSE(IsElementVisible(*panel));
+
+  // Display is none but can't be checked via InlineStyle. Adding checks of this
+  // to make sure that any one changing this assumption will have to update this
+  // test.
+  EXPECT_FALSE(panel->InlineStyle());
+  EXPECT_NE(EDisplay::kNone, panel->EnsureComputedStyle()->Display());
+}
+
 TEST_F(MediaControlsImplTest,
        RemovingFromDocumentRemovesListenersAndCallbacks) {
   auto page_holder = DummyPageHolder::Create();