Hooking up setBackgroundColor from AwContents to render process

android_webview/java/src/org/chromium/android_webview/AwContentsClient.java

Index: android_webview/java/src/org/chromium/android_webview/AwContentsClient.java
diff --git a/android_webview/java/src/org/chromium/android_webview/AwContentsClient.java b/android_webview/java/src/org/chromium/android_webview/AwContentsClient.java
index 7de19e55eeb38679b780ae37c9ca14c5a65e7038..fe42ad3a80dba7e5a7af63349c446c34fd68cf1d 100644
--- a/android_webview/java/src/org/chromium/android_webview/AwContentsClient.java
+++ b/android_webview/java/src/org/chromium/android_webview/AwContentsClient.java
@@ -52,6 +52,12 @@ public abstract class AwContentsClient {
 
     private double mDIPScale;
 
+    // Last background color reported from the renderer. Holds the sentinal value INVALID_COLOR
+    // if not valid.
+    private int mCachedRendererBackgroundColor = INVALID_COLOR;
+
+    private static final int INVALID_COLOR = 0;
+
     class AwWebContentsObserver extends WebContentsObserverAndroid {
         public AwWebContentsObserver(ContentViewCore contentViewCore) {
             super(contentViewCore);
@@ -90,6 +96,12 @@ public abstract class AwContentsClient {
     }
 
     private class AwContentViewClient extends ContentViewClient {
+        @Override
+        public void onBackgroundColorChanged(int color) {
+            // Avoid storing the sentinal INVALID_COLOR (note that both 0 and 1 are both
+            // fully transparent so this transpose makes no visible difference).
+            mCachedRendererBackgroundColor = color == INVALID_COLOR ? 1 : color;
+        }
 
         @Override
         public void onScaleChanged(float oldScale, float newScale) {
@@ -174,6 +186,15 @@ public abstract class AwContentsClient {
         return mContentViewClient;
     }
 
+    final int getCachedRendererBackgroundColor() {
+        assert isCachedRendererBackgroundColorValid();
+        return mCachedRendererBackgroundColor;
+    }
+
+    final boolean isCachedRendererBackgroundColorValid() {
+        return mCachedRendererBackgroundColor != INVALID_COLOR;
+    }
+
     //--------------------------------------------------------------------------------------------
     //             WebView specific methods that map directly to WebViewClient / WebChromeClient
     //--------------------------------------------------------------------------------------------