Add onBackgroundColorChanged to Tab and TabObserver

chrome/android/java/src/org/chromium/chrome/browser/Tab.java

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.chrome.browser;
 
 import android.app.Activity;
 import android.content.Context;
 import android.graphics.Bitmap;
 import android.graphics.Color;
@@ skipping 1016 matching lines @@
     }
 
     private void destroyNativePageInternal(NativePage nativePage) {
         if (nativePage == null) return;
         assert nativePage != mNativePage : "Attempting to destroy active page.";
 
         nativePage.destroy();
     }
 
     /**
+     * Called when the background color for the content changes.
+     * @param color The current for the background.
+     */
+    protected void onBackgroundColorChanged(int color) {
+        for (TabObserver observer : mObservers) observer.onBackgroundColorChanged(this, color);
+    }
+
+    /**
      * Destroys the current {@link ContentViewCore}.
      * @param deleteNativeWebContents Whether or not to delete the native WebContents pointer.
      */
     protected final void destroyContentViewCore(boolean deleteNativeWebContents) {
         if (mContentViewCore == null) return;
 
         destroyContentViewCoreInternal(mContentViewCore);
 
         if (mInfoBarContainer != null && mInfoBarContainer.getParent() != null) {
             mInfoBarContainer.removeFromParentView();
@@ skipping 250 matching lines @@
     private native Profile nativeGetProfileAndroid(long nativeTabAndroid);
     private native int nativeLoadUrl(long nativeTabAndroid, String url, String extraHeaders,
             byte[] postData, int transition, String referrerUrl, int referrerPolicy,
             boolean isRendererInitiated);
     private native void nativeSetActiveNavigationEntryTitleForUrl(long nativeTabAndroid, String url,
             String title);
     private native boolean nativePrint(long nativeTabAndroid);
     private native Bitmap nativeGetDefaultFavicon(long nativeTabAndroid);
     private native void nativeCreateHistoricalTab(long nativeTabAndroid);
 }