Expose a way to set a view's base background color.

public/web/WebView.h

 /*
  * Copyright (C) 2009, 2010, 2011, 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 13 matching lines @@
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef WebView_h
 #define WebView_h
 
+#include "../platform/WebColor.h"
 #include "../platform/WebString.h"
 #include "../platform/WebVector.h"
 #include "WebDragOperation.h"
 #include "WebPageVisibilityState.h"
 #include "WebWidget.h"
 
 namespace WebKit {
 
 class WebAccessibilityObject;
 class WebAutofillClient;
@@ skipping 78 matching lines @@
     // Corresponds to the encoding of the main frame.  Setting the page
     // encoding may cause the main frame to reload.
     virtual WebString pageEncoding() const = 0;
     virtual void setPageEncoding(const WebString&) = 0;
 
     // Makes the WebView transparent.  This is useful if you want to have
     // some custom background rendered behind it.
     virtual bool isTransparent() const = 0;
     virtual void setIsTransparent(bool) = 0;
 
+    // Sets the base color used for this WebView's background. This is in effect
+    // the default background color used for pages with no background-color
+    // style in effect, or used as the alpha-blended basis for any pages with
+    // translucent background-color style. (For pages with opaque
+    // background-color style, this property is effectively ignored).
+    // Setting this takes effect for the currently loaded page, if any, and
+    // persists across subsequent navigations. Defaults to white prior to the
+    // first call to this method.
+    virtual void setBaseBackgroundColor(WebColor) = 0;
+
     // Controls whether pressing Tab key advances focus to links.
     virtual bool tabsToLinks() const = 0;
     virtual void setTabsToLinks(bool) = 0;
 
     // Method that controls whether pressing Tab key cycles through page
     // elements or inserts a '\t' char in the focused text area.
     virtual bool tabKeyCyclesThroughElements() const = 0;
     virtual void setTabKeyCyclesThroughElements(bool) = 0;
 
     // Controls the WebView's active state, which may affect the rendering
@@ skipping 365 matching lines @@
 
     // Testing functionality for TestRunner ---------------------------------
 
 protected:
     ~WebView() {}
 };
 
 } // namespace WebKit
 
 #endif