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

third_party/WebKit/Source/core/frame/FrameView.cpp

Index: third_party/WebKit/Source/core/frame/FrameView.cpp
diff --git a/third_party/WebKit/Source/core/frame/FrameView.cpp b/third_party/WebKit/Source/core/frame/FrameView.cpp
index 6e8030fca4ea558c1c7cc5a6ddd66c0f999ffc1b..74e88c0066c6358f30d38ff71d7c8b4f88302538 100644
--- a/third_party/WebKit/Source/core/frame/FrameView.cpp
+++ b/third_party/WebKit/Source/core/frame/FrameView.cpp
@@ -174,7 +174,6 @@ FrameView::FrameView(LocalFrame& frame)
           TaskRunnerHelper::get(TaskType::UnspecedTimer, &frame),
           this,
           &FrameView::updatePluginsTimerFired),
-      m_isTransparent(false),
       m_baseBackgroundColor(Color::white),
       m_mediaType(MediaTypeNames::screen),
       m_safeToPropagateScrollToParent(true),
@@ -2325,20 +2324,8 @@ void FrameView::setNeedsLayout() {
   layoutViewItem.setNeedsLayout(LayoutInvalidationReason::Unknown);
 }
 
-bool FrameView::isTransparent() const {
-  return m_isTransparent;
-}
-
-void FrameView::setTransparent(bool isTransparent) {
-  m_isTransparent = isTransparent;
-  DisableCompositingQueryAsserts disabler;
-  if (!layoutViewItem().isNull() &&
-      layoutViewItem().layer()->hasCompositedLayerMapping())
-    layoutViewItem().layer()->compositedLayerMapping()->updateContentsOpaque();
-}
-
 bool FrameView::hasOpaqueBackground() const {
-  return !m_isTransparent && !m_baseBackgroundColor.hasAlpha();
+  return !m_baseBackgroundColor.hasAlpha();
 }
 
 Color FrameView::baseBackgroundColor() const {
@@ -2362,13 +2349,11 @@ void FrameView::setBaseBackgroundColor(const Color& backgroundColor) {
     page()->animator().scheduleVisualUpdate(m_frame.get());
 }
 
-void FrameView::updateBackgroundRecursively(const Color& backgroundColor,
-                                            bool transparent) {
-  forAllNonThrottledFrameViews(
-      [backgroundColor, transparent](FrameView& frameView) {
-        frameView.setTransparent(transparent);
-        frameView.setBaseBackgroundColor(backgroundColor);
-      });
+void FrameView::updateBaseBackgroundColorRecursively(
+    const Color& baseBackgroundColor) {
+  forAllNonThrottledFrameViews([baseBackgroundColor](FrameView& frameView) {
+    frameView.setBaseBackgroundColor(baseBackgroundColor);
+  });
 }
 
 void FrameView::scrollToFragmentAnchor() {