Enable smooth transition when show/hide media remoting interstitial.

third_party/WebKit/Source/core/html/shadow/MediaRemotingInterstitial.cpp

Index: third_party/WebKit/Source/core/html/shadow/MediaRemotingInterstitial.cpp
diff --git a/third_party/WebKit/Source/core/html/shadow/MediaRemotingInterstitial.cpp b/third_party/WebKit/Source/core/html/shadow/MediaRemotingInterstitial.cpp
index e183d8e59310f7094da408fae10d9a88b3cb8dd3..f38296b13caa2f55ef6c9b2a6b8d504657ccf12d 100644
--- a/third_party/WebKit/Source/core/html/shadow/MediaRemotingInterstitial.cpp
+++ b/third_party/WebKit/Source/core/html/shadow/MediaRemotingInterstitial.cpp
@@ -4,15 +4,28 @@
 
 #include "core/html/shadow/MediaRemotingInterstitial.h"
 
+#include "core/dom/TaskRunnerHelper.h"
 #include "core/html/HTMLImageElement.h"
 #include "core/html/HTMLVideoElement.h"
 #include "core/html/shadow/MediaRemotingElements.h"
 
+namespace {
+
+constexpr double kStyleChangeTransSeconds = 0.2;
+constexpr double kHiddenAnimationSeconds = 0.3;
+
+}  // namespace
+
 namespace blink {
 
 MediaRemotingInterstitial::MediaRemotingInterstitial(
     HTMLVideoElement& videoElement)
     : HTMLDivElement(videoElement.GetDocument()),
+      toggle_insterstitial_timer_(
+          TaskRunnerHelper::Get(TaskType::kUnthrottled,
+                                &videoElement.GetDocument()),
+          this,
+          &MediaRemotingInterstitial::ToggleInterstitialTimerFired),
       video_element_(&videoElement) {
   SetShadowPseudoId(AtomicString("-internal-media-remoting-interstitial"));
   background_image_ = HTMLImageElement::Create(videoElement.GetDocument());
@@ -32,13 +45,43 @@ MediaRemotingInterstitial::MediaRemotingInterstitial(
 }
 
 void MediaRemotingInterstitial::Show() {
+  DCHECK(!should_be_visible_);
+  if (toggle_insterstitial_timer_.IsActive())
+    toggle_insterstitial_timer_.Stop();
+  should_be_visible_ = true;
   RemoveInlineStyleProperty(CSSPropertyDisplay);
   exit_button_->OnShown();
+  toggle_insterstitial_timer_.StartOneShot(kStyleChangeTransSeconds,
+                                           BLINK_FROM_HERE);
 }
 
 void MediaRemotingInterstitial::Hide() {
-  SetInlineStyleProperty(CSSPropertyDisplay, CSSValueNone);
+  DCHECK(should_be_visible_);
+  if (toggle_insterstitial_timer_.IsActive())
+    toggle_insterstitial_timer_.Stop();
+  should_be_visible_ = false;
+  SetInlineStyleProperty(CSSPropertyOpacity, 0,
+                         CSSPrimitiveValue::UnitType::kNumber);
   exit_button_->OnHidden();
+  toggle_insterstitial_timer_.StartOneShot(kHiddenAnimationSeconds,
+                                           BLINK_FROM_HERE);
+}
+
+void MediaRemotingInterstitial::ToggleInterstitialTimerFired(TimerBase*) {
+  toggle_insterstitial_timer_.Stop();
+  if (should_be_visible_) {
+    SetInlineStyleProperty(CSSPropertyOpacity, 1,
+                           CSSPrimitiveValue::UnitType::kNumber);
+  } else {
+    SetInlineStyleProperty(CSSPropertyDisplay, CSSValueNone);
+  }
+}
+
+void MediaRemotingInterstitial::DidMoveToNewDocument(Document& old_document) {
+  toggle_insterstitial_timer_.MoveToNewTaskRunner(
+      TaskRunnerHelper::Get(TaskType::kUnthrottled, &GetDocument()));
+
+  HTMLDivElement::DidMoveToNewDocument(old_document);
 }
 
 void MediaRemotingInterstitial::OnPosterImageChanged() {