Update poster code as per https://html.spec.whatwg.org/#show-poster-flag

third_party/WebKit/Source/core/html/HTMLVideoElement.cpp

Index: third_party/WebKit/Source/core/html/HTMLVideoElement.cpp
diff --git a/third_party/WebKit/Source/core/html/HTMLVideoElement.cpp b/third_party/WebKit/Source/core/html/HTMLVideoElement.cpp
index fe5170644016ab7a1e42efe73e22ff1a051996b1..1d23185800daf4c826720073df69450ba6c81dce 100644
--- a/third_party/WebKit/Source/core/html/HTMLVideoElement.cpp
+++ b/third_party/WebKit/Source/core/html/HTMLVideoElement.cpp
@@ -52,6 +52,7 @@ using namespace HTMLNames;
 
 inline HTMLVideoElement::HTMLVideoElement(Document& document)
     : HTMLMediaElement(videoTag, document)
+    , m_showPoster(true)
 {
     if (document.settings())
         m_defaultPosterURL = AtomicString(document.settings()->defaultVideoPosterURL());
@@ -85,7 +86,6 @@ void HTMLVideoElement::attach(const AttachContext& context)
 {
     HTMLMediaElement::attach(context);
 
-    updateDisplayState();
     if (shouldDisplayPosterImage()) {
         if (!m_imageLoader)
             m_imageLoader = HTMLImageLoader::create(this);
@@ -115,13 +115,6 @@ bool HTMLVideoElement::isPresentationAttribute(const QualifiedName& name) const
 void HTMLVideoElement::parseAttribute(const QualifiedName& name, const AtomicString& value)
 {
     if (name == posterAttr) {
-        // In case the poster attribute is set after playback, don't update the
-        // display state, post playback the correct state will be picked up.
-        if (displayMode() < Video || !hasAvailableVideoFrame()) {
-            // Force a poster recalc by setting m_displayMode to Unknown directly before calling updateDisplayState.
-            HTMLMediaElement::setDisplayMode(Unknown);
-            updateDisplayState();
-        }
         if (!posterImageURL().isEmpty()) {
             if (!m_imageLoader)
                 m_imageLoader = HTMLImageLoader::create(this);
@@ -165,9 +158,8 @@ const AtomicString HTMLVideoElement::imageSourceURL() const
     return m_defaultPosterURL;
 }
 
-void HTMLVideoElement::setDisplayMode(DisplayMode mode)
+void HTMLVideoElement::setShowPoster(bool showPoster)
 {
-    DisplayMode oldMode = displayMode();
     KURL poster = posterImageURL();
 
     if (!poster.isEmpty()) {
@@ -175,22 +167,15 @@ void HTMLVideoElement::setDisplayMode(DisplayMode mode)
         // media engine has something to display.
         // Don't show the poster if there is a seek operation or
         // the video has restarted because of loop attribute
-        if (mode == Video && oldMode == Poster && !hasAvailableVideoFrame())
+        if (!showPoster && m_showPoster && !hasAvailableVideoFrame())
             return;
     }
 
-    HTMLMediaElement::setDisplayMode(mode);
-
-    if (layoutObject() && displayMode() != oldMode)
-        layoutObject()->updateFromElement();
-}
-
-void HTMLVideoElement::updateDisplayState()
-{
-    if (posterImageURL().isEmpty())
-        setDisplayMode(Video);
-    else if (displayMode() < Poster)
-        setDisplayMode(Poster);
+    if (showPoster != m_showPoster) {
+        m_showPoster = showPoster;
+        if (layoutObject())
+            layoutObject()->updateFromElement();
+    }
 }
 
 void HTMLVideoElement::paintCurrentFrame(SkCanvas* canvas, const IntRect& destRect, const SkPaint* paint) const