Sets a transparent background for out-of-process subframes.

third_party/WebKit/Source/web/WebFrameWidgetImpl.cpp

Index: third_party/WebKit/Source/web/WebFrameWidgetImpl.cpp
diff --git a/third_party/WebKit/Source/web/WebFrameWidgetImpl.cpp b/third_party/WebKit/Source/web/WebFrameWidgetImpl.cpp
index 033a49e59fb956e16f9f9914cd55df6e48e7975b..8c2c3ce044c028b60906d36df583cc33bb5cc898 100644
--- a/third_party/WebKit/Source/web/WebFrameWidgetImpl.cpp
+++ b/third_party/WebKit/Source/web/WebFrameWidgetImpl.cpp
@@ -63,7 +63,10 @@ namespace blink {
 WebFrameWidget* WebFrameWidget::create(WebWidgetClient* client, WebLocalFrame* localRoot)
 {
     // Pass the WebFrameWidget's self-reference to the caller.
-    return WebFrameWidgetImpl::create(client, localRoot);
+    WebFrameWidgetImpl* widget = WebFrameWidgetImpl::create(client, localRoot);
+    if (localRoot->parent())

[dcheng, 2016/02/11 22:40:26]

Do you think it'd make sense to have this in the ctor? That way, if someone
accidentally calls WebFrameWidgetImpl::create(), they still get the right
default.

[lfg, 2016/02/11 23:48:02]

Done.

+        widget->setIsTransparent(true);
+    return widget;
 }
 
 WebFrameWidget* WebFrameWidget::create(WebWidgetClient* client, WebView* webView, WebLocalFrame* mainFrame)
@@ -98,6 +101,7 @@ WebFrameWidgetImpl::WebFrameWidgetImpl(WebWidgetClient* client, WebLocalFrame* l
     , m_layerTreeViewClosed(false)
     , m_suppressNextKeypressEvent(false)
     , m_ignoreInputEvents(false)
+    , m_isTransparent(false)
 #if ENABLE(OILPAN)
     , m_selfKeepAlive(this)
 #endif
@@ -278,7 +282,7 @@ void WebFrameWidgetImpl::updateLayerTreeBackgroundColor()
     if (!m_layerTreeView)
         return;
 
-    m_layerTreeView->setBackgroundColor(alphaChannel(view()->backgroundColorOverride()) ? view()->backgroundColorOverride() : view()->backgroundColor());
+    m_layerTreeView->setBackgroundColor(backgroundColor());
 }
 
 void WebFrameWidgetImpl::updateLayerTreeDeviceScaleFactor()
@@ -290,10 +294,17 @@ void WebFrameWidgetImpl::updateLayerTreeDeviceScaleFactor()
     m_layerTreeView->setDeviceScaleFactor(deviceScaleFactor);
 }
 
+void WebFrameWidgetImpl::setIsTransparent(bool isTransparent)
+{
+    m_isTransparent = isTransparent;
+

[dcheng, 2016/02/11 22:40:26]

The WebView version also marks the FrameViews as transparent: do we need
anything like that?

[lfg, 2016/02/11 23:48:02]

I believe this is correct. isTransparent() on FrameView only controls painting
the background if it's the main frame (iframes are transparent by default), and
controls things that should be treated differently when the main frame's
background is transparent. In this case, the main frame is not transparent, we
just want to drop the background layer in the local root's widget.

However, we may want to set the frameviews as transparent when the WebViewImpl
in the main frame is set as transparent, but looking at usages of
FrameView::isTransparent(), I don't think we are breaking anything by not
replicating this parameter.

[dcheng, 2016/02/12 22:46:23]

Hm... I guess I am thinking that it would make it easier to merge widget
portions of WebView into WebFrameWidget into the future. But I guess at that
point, we'll have to manually diff and reconcile any behavior differences...
maybe a TODO could be useful though.

+    if (m_layerTreeView)
+        m_layerTreeView->setHasTransparentBackground(isTransparent);
+}
+
 bool WebFrameWidgetImpl::isTransparent() const
 {
-    // FIXME: This might need to proxy to the WebView's isTransparent().
-    return false;
+    return m_isTransparent;
 }
 
 void WebFrameWidgetImpl::layoutAndPaintAsync(WebLayoutAndPaintAsyncCallback* callback)
@@ -381,6 +392,18 @@ bool WebFrameWidgetImpl::hasTouchEventHandlersAt(const WebPoint& point)
     return true;
 }
 
+void WebFrameWidgetImpl::setBaseBackgroundColor(WebColor color)
+{
+    if (m_baseBackgroundColor == color)
+        return;
+
+    m_baseBackgroundColor = color;
+
+    m_localRoot->frameView()->setBaseBackgroundColor(color);
+
+    updateAllLifecyclePhases();
+}
+
 void WebFrameWidgetImpl::scheduleAnimation()
 {
     if (m_layerTreeView) {
@@ -483,7 +506,7 @@ WebColor WebFrameWidgetImpl::backgroundColor() const
     if (isTransparent())
         return Color::transparent;
     if (!m_localRoot->frameView())
-        return view()->backgroundColor();
+        return m_baseBackgroundColor;
     FrameView* view = m_localRoot->frameView();
     return view->documentBackgroundColor().rgb();
 }