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

Source/web/WebViewImpl.cpp

Index: Source/web/WebViewImpl.cpp
diff --git a/Source/web/WebViewImpl.cpp b/Source/web/WebViewImpl.cpp
index e525031ce93686e42f3caf18ad834c0a7c5ad6bd..892e595750d75035e5ef6b1fb2f866a0ff454a06 100644
--- a/Source/web/WebViewImpl.cpp
+++ b/Source/web/WebViewImpl.cpp
@@ -138,7 +138,6 @@
 #include "core/platform/chromium/KeyboardCodes.h"
 #include "core/platform/chromium/TraceEvent.h"
 #include "core/platform/chromium/support/WebActiveGestureAnimation.h"
-#include "core/platform/graphics/Color.h"
 #include "core/platform/graphics/ColorSpace.h"
 #include "core/platform/graphics/Extensions3D.h"
 #include "core/platform/graphics/FontCache.h"
@@ -427,6 +426,7 @@ WebViewImpl::WebViewImpl(WebViewClient* client)
     , m_showDebugBorders(false)
     , m_continuousPaintingEnabled(false)
     , m_showScrollBottleneckRects(false)
+    , m_baseBackgroundColor(Color::white)
 {
     Page::PageClients pageClients;
     pageClients.chromeClient = &m_chromeClientImpl;
@@ -2459,11 +2459,11 @@ WebColor WebViewImpl::backgroundColor() const
     if (isTransparent())
         return Color::transparent;
     if (!m_page)
-        return Color::white;
+        return m_baseBackgroundColor.rgb();
     FrameView* view = m_page->mainFrame()->view();
     Color backgroundColor = view->documentBackgroundColor();
     if (!backgroundColor.isValid())
-        return Color::white;
+        return m_baseBackgroundColor.rgb();
     return backgroundColor.rgb();
 }
 
@@ -3571,6 +3571,17 @@ void WebViewImpl::setIsTransparent(bool isTransparent)
     m_isTransparent = isTransparent;
 }
 
+void WebViewImpl::setBaseBackgroundColor(WebColor color)

[aelias_OOO_until_Jul13, 2013/07/23 19:05:01]

Please add an early return if the color hasn't changed.

[joth, 2013/07/23 21:13:16]

Done

+{
+    m_baseBackgroundColor = Color(static_cast<RGBA32>(color));
+    m_isTransparent = !m_baseBackgroundColor.alpha();

[aelias_OOO_until_Jul13, 2013/07/23 19:02:16]

This is testing for complete transparency, but isn't partial transparency
enough?  I think this should probably be:

m_isTransparent = m_baseBackgroundColor.hasAlpha();

(which tests for alpha() < 255).

[joth, 2013/07/23 21:13:16]

My reading of WebViewImpl::backgroundColor() is that m_isTransparent == true
means that the background is 100% transparent: it short-circuits calculating any
background color and just returns Color::transparent.

Ah... so that means WebView::setTransparent() *overrides* and CSS
background-color, c.f. setBaseBackgroundColor which does not.  So, I've removed
this line from here.

Done

+
+    m_page->mainFrame()->view()->updateBackgroundRecursively(m_baseBackgroundColor, m_isTransparent);
+
+    if (m_layerTreeView)
+        m_layerTreeView->setBackgroundColor(backgroundColor());
+}
+
 bool WebViewImpl::isTransparent() const
 {
     return m_isTransparent;