Introduce ViewRoot forwarding input/view events to native

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

Index: chrome/android/java/src/org/chromium/chrome/browser/tab/Tab.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/tab/Tab.java b/chrome/android/java/src/org/chromium/chrome/browser/tab/Tab.java
index 699d62ed8f1c24ab7666633e9e6b27b154d95428..44e799b3f0cf5cc36755183970814e79cf77db41 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/tab/Tab.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/tab/Tab.java
@@ -107,6 +107,7 @@ import org.chromium.printing.PrintingControllerImpl;
 import org.chromium.ui.base.LocalizationUtils;
 import org.chromium.ui.base.PageTransition;
 import org.chromium.ui.base.ViewAndroidDelegate;
+import org.chromium.ui.base.ViewRoot;
 import org.chromium.ui.base.WindowAndroid;
 import org.chromium.ui.mojom.WindowOpenDisposition;
 
@@ -187,6 +188,9 @@ public class Tab implements ViewGroup.OnHierarchyChangeListener,
     /** {@link ContentViewCore} showing the current page, or {@code null} if the tab is frozen. */
     private ContentViewCore mContentViewCore;
 
+    /** {@link ViewRoot} used to forward input/view events down to native. */
+    private ViewRoot mViewRoot;
+
     /** Listens to gesture events fired by the ContentViewCore. */
     private GestureStateListener mGestureStateListener;
 
@@ -1625,6 +1629,13 @@ public class Tab implements ViewGroup.OnHierarchyChangeListener,
     }
 
     /**
+     * @return {@link ViewRoot} instance used to forward view/input events.
+     */
+    public ViewRoot getViewRoot() {
+        return mViewRoot;
+    }
+
+    /**
      * Called when a navigation begins and no navigation was in progress
      * @param toDifferentDocument Whether this navigation will transition between
      * documents (i.e., not a fragment navigation or JS History API call).
@@ -1724,6 +1735,8 @@ public class Tab implements ViewGroup.OnHierarchyChangeListener,
         ChromeActionModeCallback actionModeCallback = new ChromeActionModeCallback(
                 mThemedApplicationContext, this, cvc.getActionModeCallbackHelper());
         cvc.setActionModeCallback(actionModeCallback);
+        mViewRoot = ViewRoot.create(mWindowAndroid);
+        webContents.initViewRoot(mViewRoot);
         return cvc;
     }
 
@@ -2459,8 +2472,7 @@ public class Tab implements ViewGroup.OnHierarchyChangeListener,
         // (see http://crbug.com/340987).
         newContentViewCore.onSizeChanged(originalWidth, originalHeight, 0, 0);
         if (!bounds.isEmpty()) {
-            newContentViewCore.getWindowAndroid().getViewRoot().onPhysicalBackingSizeChanged(
-                    bounds.right, bounds.bottom);
+            getViewRoot().onPhysicalBackingSizeChanged(bounds.right, bounds.bottom);
         }
         newContentViewCore.onShow();
         setContentViewCore(newContentViewCore);