Expose WindowAndroid from WebContents.

content/public/android/java/src/org/chromium/content/browser/webcontents/WebContentsImpl.java

Index: content/public/android/java/src/org/chromium/content/browser/webcontents/WebContentsImpl.java
diff --git a/content/public/android/java/src/org/chromium/content/browser/webcontents/WebContentsImpl.java b/content/public/android/java/src/org/chromium/content/browser/webcontents/WebContentsImpl.java
index 5150f32ab82bffca49276be51d3bdd3ef9b9b305..86854dce956bb94e7a71c095df2bc112e780eabc 100644
--- a/content/public/android/java/src/org/chromium/content/browser/webcontents/WebContentsImpl.java
+++ b/content/public/android/java/src/org/chromium/content/browser/webcontents/WebContentsImpl.java
@@ -30,6 +30,7 @@ import org.chromium.content_public.browser.WebContents;
 import org.chromium.content_public.browser.WebContentsObserver;
 import org.chromium.ui.OverscrollRefreshHandler;
 import org.chromium.ui.accessibility.AXTextStyle;
+import org.chromium.ui.base.WindowAndroid;
 
 import java.util.ArrayList;
 import java.util.List;
@@ -144,6 +145,11 @@ import java.util.UUID;
     }
 
     @Override
+    public WindowAndroid getTopLevelNativeWindow() {
+        return nativeGetTopLevelNativeWindow(mNativeWebContentsAndroid);
+    }
+
+    @Override
     public void destroy() {
         if (!ThreadUtils.runningOnUiThread()) {
             throw new IllegalStateException("Attempting to destroy WebContents on non-UI thread");
@@ -500,6 +506,7 @@ import java.util.UUID;
 
     private static native WebContents nativeFromNativePtr(long webContentsAndroidPtr);
 
+    private native WindowAndroid nativeGetTopLevelNativeWindow(long nativeWebContentsAndroid);
     private native String nativeGetTitle(long nativeWebContentsAndroid);
     private native String nativeGetVisibleURL(long nativeWebContentsAndroid);
     private native boolean nativeIsLoading(long nativeWebContentsAndroid);