Introduce ViewRoot to forward input/view events to native

ui/android/java/src/org/chromium/ui/base/WindowAndroid.java

Index: ui/android/java/src/org/chromium/ui/base/WindowAndroid.java
diff --git a/ui/android/java/src/org/chromium/ui/base/WindowAndroid.java b/ui/android/java/src/org/chromium/ui/base/WindowAndroid.java
index 88f64bda1a6cb1e0746abc7bd904cc7b1bebef03..9fece450858f867a229d2a59e1a9821d48212212 100644
--- a/ui/android/java/src/org/chromium/ui/base/WindowAndroid.java
+++ b/ui/android/java/src/org/chromium/ui/base/WindowAndroid.java
@@ -110,6 +110,8 @@ public class WindowAndroid {
 
     private AndroidPermissionDelegate mPermissionDelegate;
 
+    private ViewRoot mViewRoot;
+
     /**
      * An interface to notify listeners of changes in the soft keyboard's visibility.
      */
@@ -727,6 +729,16 @@ public class WindowAndroid {
         }
     }
 
+    /**
+     * @return {@link ViewRoot} instance used to forward input/view events down to native.
+     */
+    public ViewRoot getViewRoot() {
+        if (mViewRoot == null) {
+            mViewRoot = nativeGetViewRootForJava(mNativeWindowAndroid);
+        }
+        return mViewRoot;
+    }
+
     private native long nativeInit(int displayId);
     private native void nativeOnVSync(long nativeWindowAndroid,
                                       long vsyncTimeMicros,
@@ -735,5 +747,5 @@ public class WindowAndroid {
     private native void nativeOnActivityStopped(long nativeWindowAndroid);
     private native void nativeOnActivityStarted(long nativeWindowAndroid);
     private native void nativeDestroy(long nativeWindowAndroid);
-
+    private native ViewRoot nativeGetViewRootForJava(long nativeWindowAndroid);
 }