[blink] Support (semi-)transparent background colors in WebView/Frame.

third_party/WebKit/Source/web/FullscreenController.cpp

Index: third_party/WebKit/Source/web/FullscreenController.cpp
diff --git a/third_party/WebKit/Source/web/FullscreenController.cpp b/third_party/WebKit/Source/web/FullscreenController.cpp
index 4380a01fb2d69c41051ae38c536576db7c821aac..c6a12fd7a65086fa20ee73073c0fe68a7a2c0747 100644
--- a/third_party/WebKit/Source/web/FullscreenController.cpp
+++ b/third_party/WebKit/Source/web/FullscreenController.cpp
@@ -182,6 +182,10 @@ void FullscreenController::fullscreenElementChanged(Element* fromElement,
                                                     Element* toElement) {
   DCHECK_NE(fromElement, toElement);
 
+  // Restore transparency if old fullscreen element changed it.
+  if (m_needsTransparencyRestore)
+    m_webViewImpl->setIsTransparent(m_initialTransparency);
+
   if (toElement) {
     DCHECK(Fullscreen::isCurrentFullScreenElement(*toElement));
 
@@ -191,9 +195,10 @@ void FullscreenController::fullscreenElementChanged(Element* fromElement,
 
       // If the video uses overlay fullscreen mode, make the background
       // transparent.
-      if (videoElement.usesOverlayFullscreenVideo() &&
-          m_webViewImpl->layerTreeView()) {
-        m_webViewImpl->layerTreeView()->setHasTransparentBackground(true);
+      if (videoElement.usesOverlayFullscreenVideo()) {
+        m_initialTransparency = m_webViewImpl->isTransparent();

[chrishtr, 2017/03/01 16:16:53]

For m_initialPageScaleFactor, it is "reset" in
FullscreenController::didUpdateLayout. Why is that done there and
your new value reset in fullscreenElementChanged?

[Eric Seckler, 2017/03/07 18:00:46]

This stuff changed a bit now, but I still restore within
fullscreenElementChanged. I added a few comments explaining why.

+        m_needsTransparencyRestore = true;
+        m_webViewImpl->setIsTransparent(true);
       }
     }
   }
@@ -202,12 +207,6 @@ void FullscreenController::fullscreenElementChanged(Element* fromElement,
     DCHECK(!Fullscreen::isCurrentFullScreenElement(*fromElement));
 
     if (isHTMLVideoElement(*fromElement)) {
-      // If the video used overlay fullscreen mode, restore the transparency.
-      if (m_webViewImpl->layerTreeView()) {
-        m_webViewImpl->layerTreeView()->setHasTransparentBackground(
-            m_webViewImpl->isTransparent());
-      }
-
       HTMLVideoElement& videoElement = toHTMLVideoElement(*fromElement);
       videoElement.didExitFullscreen();
     }