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..9a38f313b272f7f052f860296963b747fde332ba 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 +86,7 @@ void HTMLVideoElement::attach(const AttachContext& context)
 {
     HTMLMediaElement::attach(context);
 
-    updateDisplayState();
+    updateDisplayState(true);
     if (shouldDisplayPosterImage()) {
         if (!m_imageLoader)
             m_imageLoader = HTMLImageLoader::create(this);
@@ -117,10 +118,9 @@ void HTMLVideoElement::parseAttribute(const QualifiedName& name, const AtomicStr
     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 (m_showPoster || !hasAvailableVideoFrame()) {
+            m_showPoster = true;
+            updateDisplayState(true);
         }
         if (!posterImageURL().isEmpty()) {
             if (!m_imageLoader)
@@ -165,9 +165,8 @@ 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 +174,26 @@ 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();
+    if (showPoster != m_showPoster) {
+        m_showPoster = showPoster;
+        if (layoutObject())
+            layoutObject()->updateFromElement();
+    }
 }
 
-void HTMLVideoElement::updateDisplayState()
+void HTMLVideoElement::updateDisplayState(bool forceUpdate)

[philipj_slow, 2015/10/01 09:45:59]

This whole method looks suspicifous to me, it doesn't correspond to anything in
the spec. It would be good to start out by only using the show poster flag in
precisely the places the spec says, and then see what breaks. Wherever you need
to add something, we probably have a spec to fix as well.

 {
-    if (posterImageURL().isEmpty())
-        setDisplayMode(Video);
-    else if (displayMode() < Poster)
-        setDisplayMode(Poster);
+    if (posterImageURL().isEmpty()) {
+        setShowPoster(false);
+    } else if (m_showPoster) {
+        if (forceUpdate)
+            m_showPoster = false;
+        setShowPoster(true);
+    }
 }
 
 void HTMLVideoElement::paintCurrentFrame(SkCanvas* canvas, const IntRect& destRect, const SkPaint* paint) const