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

third_party/WebKit/Source/web/WebViewImpl.cpp

Index: third_party/WebKit/Source/web/WebViewImpl.cpp
diff --git a/third_party/WebKit/Source/web/WebViewImpl.cpp b/third_party/WebKit/Source/web/WebViewImpl.cpp
index b2f519640487e074aacef9a69bc6cf000f1a93ab..e58529813fd3d5071318478f387c5bf3bd4bef44 100644
--- a/third_party/WebKit/Source/web/WebViewImpl.cpp
+++ b/third_party/WebKit/Source/web/WebViewImpl.cpp
@@ -360,7 +360,6 @@ WebViewImpl::WebViewImpl(WebViewClient* client,
       m_suppressNextKeypressEvent(false),
       m_imeAcceptEvents(true),
       m_devToolsEmulator(nullptr),
-      m_isTransparent(false),
       m_tabsToLinks(false),
       m_layerTreeView(nullptr),
       m_rootLayer(nullptr),
@@ -373,6 +372,7 @@ WebViewImpl::WebViewImpl(WebViewClient* client,
       m_baseBackgroundColor(Color::white),
       m_baseBackgroundColorOverrideEnabled(false),
       m_baseBackgroundColorOverride(Color::transparent),
+      m_backgroundColorOverrideEnabled(false),
       m_backgroundColorOverride(Color::transparent),
       m_zoomFactorOverride(0),
       m_userGestureObserved(false),
@@ -2445,8 +2445,8 @@ bool WebViewImpl::isSelectionAnchorFirst() const {
 }
 
 WebColor WebViewImpl::backgroundColor() const {
-  if (isTransparent())
-    return Color::transparent;
+  if (m_backgroundColorOverrideEnabled)
+    return m_backgroundColorOverride;
   if (!m_page)
     return baseBackgroundColor().rgb();
   if (!m_page->mainFrame())
@@ -2454,6 +2454,8 @@ WebColor WebViewImpl::backgroundColor() const {
   if (!m_page->mainFrame()->isLocalFrame())
     return baseBackgroundColor().rgb();
   FrameView* view = m_page->deprecatedLocalMainFrame()->view();
+  if (!view)
+    return baseBackgroundColor().rgb();
   return view->documentBackgroundColor().rgb();
 }
 
@@ -3516,26 +3518,6 @@ void WebViewImpl::hidePopups() {
   cancelPagePopup();
 }
 
-void WebViewImpl::setIsTransparent(bool isTransparent) {
-  // Set any existing frames to be transparent.
-  Frame* frame = m_page->mainFrame();
-  while (frame) {
-    if (frame->isLocalFrame())
-      toLocalFrame(frame)->view()->setTransparent(isTransparent);
-    frame = frame->tree().traverseNext();
-  }
-
-  // Future frames check this to know whether to be transparent.
-  m_isTransparent = isTransparent;
-
-  if (m_layerTreeView)
-    m_layerTreeView->setHasTransparentBackground(this->isTransparent());
-}
-
-bool WebViewImpl::isTransparent() const {
-  return m_isTransparent;
-}
-
 WebInputMethodControllerImpl* WebViewImpl::getActiveWebInputMethodController()
     const {
   return WebInputMethodControllerImpl::fromFrame(focusedLocalFrameInWidget());
@@ -3583,8 +3565,11 @@ void WebViewImpl::clearBaseBackgroundColorOverride() {
 
 void WebViewImpl::updateBaseBackgroundColor() {
   Color color = baseBackgroundColor();
-  if (m_page->mainFrame() && m_page->mainFrame()->isLocalFrame())
-    m_page->deprecatedLocalMainFrame()->view()->setBaseBackgroundColor(color);
+  if (m_page->mainFrame() && m_page->mainFrame()->isLocalFrame()) {
+    FrameView* view = m_page->deprecatedLocalMainFrame()->view();
+    view->setBaseBackgroundColor(color);
+    view->updateBaseBackgroundColorRecursively(color);

[chrishtr, 2017/03/28 19:45:56]

Why this new line?

[Eric Seckler, 2017/03/29 10:50:18]

setIsTransparent was previously setting the transparency bit on all existing
FrameViews. It needed to do that, because it was called when some FrameViews may
already exist.

Now that we are using the baseBackgroundColor(Override) to enable transparency,
setBaseBackgroundColor may be called when some FrameViews already exist. (I
don't think the baseBackgroundColor was previously intended to change after
initial WebViewImpl creation.) In any case, we now need to pass on the
baseBackgroundColor update to all existing FrameViews, so that we preserve a
behavior similar to what setIsTransparent did previously.

[chrishtr, 2017/03/29 15:36:41]

Ok.

+  }
 }
 
 void WebViewImpl::setIsActive(bool active) {
@@ -3710,10 +3695,16 @@ bool WebViewImpl::useExternalPopupMenus() {
 }
 
 void WebViewImpl::setBackgroundColorOverride(WebColor color) {
+  m_backgroundColorOverrideEnabled = true;
   m_backgroundColorOverride = color;
   updateLayerTreeBackgroundColor();
 }
 
+void WebViewImpl::clearBackgroundColorOverride() {
+  m_backgroundColorOverrideEnabled = false;
+  updateLayerTreeBackgroundColor();
+}
+
 void WebViewImpl::setZoomFactorOverride(float zoomFactor) {
   m_zoomFactorOverride = zoomFactor;
   setZoomLevel(zoomLevel());
@@ -4023,10 +4014,7 @@ void WebViewImpl::updateLayerTreeViewport() {
 void WebViewImpl::updateLayerTreeBackgroundColor() {
   if (!m_layerTreeView)
     return;
-
-  m_layerTreeView->setBackgroundColor(alphaChannel(m_backgroundColorOverride)
-                                          ? m_backgroundColorOverride
-                                          : backgroundColor());
+  m_layerTreeView->setBackgroundColor(backgroundColor());
 }
 
 void WebViewImpl::updateLayerTreeDeviceScaleFactor() {