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

third_party/WebKit/Source/web/WebViewImpl.h

Index: third_party/WebKit/Source/web/WebViewImpl.h
diff --git a/third_party/WebKit/Source/web/WebViewImpl.h b/third_party/WebKit/Source/web/WebViewImpl.h
index f94b6956b3eff9c0cca24d8d0e9e61df62f8963c..30b1917753d1cbf782a4f51df5afc811eb100ceb 100644
--- a/third_party/WebKit/Source/web/WebViewImpl.h
+++ b/third_party/WebKit/Source/web/WebViewImpl.h
@@ -288,12 +288,16 @@ class WEB_EXPORT WebViewImpl final
   void setBaseBackgroundColorOverride(WebColor);
   void clearBaseBackgroundColorOverride();
   void setBackgroundColorOverride(WebColor);
+  void clearBackgroundColorOverride();
   void setZoomFactorOverride(float);
   void setCompositorDeviceScaleFactorOverride(float);
   void setDeviceEmulationTransform(const TransformationMatrix&);
   TransformationMatrix getDeviceEmulationTransformForTesting() const;
 
   Color baseBackgroundColor() const;
+  bool backgroundColorOverrideEnabled() const {
+    return m_backgroundColorOverrideEnabled;
+  }
   WebColor backgroundColorOverride() const { return m_backgroundColorOverride; }
 
   Frame* focusedCoreFrame() const;
@@ -494,9 +498,6 @@ class WEB_EXPORT WebViewImpl final
 
   FloatSize elasticOverscroll() const { return m_elasticOverscroll; }
 
-  bool isTransparent() const;
-  void setIsTransparent(bool value);
-
   double lastFrameTimeMonotonic() const { return m_lastFrameTimeMonotonic; }
 
   ChromeClientImpl& chromeClient() const { return *m_chromeClientImpl.get(); }
@@ -677,9 +678,6 @@ class WEB_EXPORT WebViewImpl final
   Persistent<DevToolsEmulator> m_devToolsEmulator;
   std::unique_ptr<PageOverlay> m_pageColorOverlay;
 
-  // Whether the webview is rendering transparently.
-  bool m_isTransparent;
-
   // Whether the user can press tab to focus links.
   bool m_tabsToLinks;
 
@@ -709,6 +707,7 @@ class WEB_EXPORT WebViewImpl final
   WebColor m_baseBackgroundColor;
   bool m_baseBackgroundColorOverrideEnabled;
   WebColor m_baseBackgroundColorOverride;
+  bool m_backgroundColorOverrideEnabled;
   WebColor m_backgroundColorOverride;
   float m_zoomFactorOverride;