Steps to reproduce the problem:
1. We have create a browser app that use the chromium;
2. Start up the Browser;
3. Display the expandable site(https://www.yahoo.co.jp/);
4. Then use webview.zoomIn() to enlarge the display size.

What is the expected behavior?
After step 4, Enlarging starting from the center of the screen.

What went wrong?
After step 4, It is enlarging starting from the right side of the screen.

Did this work before? N/A 

Chrome version: 58.0.3029.82  Channel: beta
OS Version: 7.1
Flash Version: 

1. In M, it was enlarging starting from the center of the screen. From the user's view, the operation of M is better.
2. In the case of a pinch operation, it was enlarged starting from the space between two fingers (as expected).
3. We updated the version of WebView to 57.0.2987.132, but the behavior has not changed.It is not difference of OS (M and N), it is estimated as difference of operation by WebView version.
4. Using N, we tried the following three patterns of WebView implementation, but the problems are reproduced in either case.
   ・Chrome Beta  ：58.0.3029.82
   ・Chrome Dev   ：59.0.3031.25
   ・Chrome Canary：60.0.3082.0
5. Used the following WebView API 
It used this method：
===========================
webview.zoomIn(); 
===========================
I checked the webview code and found it:
In chromium/WebViewChromium.java:
================================
public boolean zoomIn() {
   mFactory.startYourEngines(true);
   if (checkNeedsPost()) {
       boolean ret = runOnUiThreadBlocking(new Callable<Boolean>() {
           @Override
           public Boolean call() {
               return zoomIn();
           }
       });
       return ret;
   }
   return mAwContents.zoomIn();
}
===============================
In chromium/android_webview/AwContents.java:
===============================
public boolean zoomIn() {
   if (!canZoomIn()) {
       return false;
   }
   return zoomBy(1.25f);
}
... ...
public boolean zoomBy(float delta) {
   if (isDestroyed()) return false;
   if (delta < 0.01f || delta > 100.0f) {
       throw new IllegalStateException("zoom delta value outside [0.01, 100] range.");
   }
   return mContentViewCore.pinchByDelta(delta);
}
=================================================
In chromium/content/browser/ContentViewCore.java:
=================================================
public boolean pinchByDelta(float delta) {
   if (mNativeContentViewCore == 0) return false;

   long timeMs = SystemClock.uptimeMillis();
   int xPix = getViewportWidthPix() / 2;
   int yPix = getViewportHeightPix() / 2;

   nativePinchBegin(mNativeContentViewCore, timeMs, xPix, yPix);
   nativePinchBy(mNativeContentViewCore, timeMs, xPix, yPix, delta);
   nativePinchEnd(mNativeContentViewCore, timeMs);

   return true;
}
=================================================