See also issue 763157, though that regressed in M62.

Caused by https://chromium.googlesource.com/chromium/src/+/86071c86ba17eb7761cd0663bc95ceaaf3c4fb77?

looks like we used to call mTab.getContentViewCore().onSizeChanged(surfaceWidth, surfaceHeight, 0, 0), but on longer do in VRShellImpl.java

We do now call web_contents->GetNativeView()->OnSizeChanged(width, height); instead, but I'm not sure whether this updates all aspects of the size.

Michael, could you please take a look?

This also shows how important it is that we get pixel smoke tests that can catch this class of regression.

That was a mistake - CVC.onSizeChanged() is still necessary. I'll fix it.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/93edb8ef2b37b4157b5efd27f543b20c07af725e

commit 93edb8ef2b37b4157b5efd27f543b20c07af725e
Author: Jinsuk Kim <jinsukkim@chromium.org>
Date: Mon Sep 11 00:18:48 2017

Fix a bug scaling VR pages incorrectly

A call to CVC.onSizeChanged() got removed by mistake in
https://crrev.com/c/634847. This CL fixes it by putting
the call back in.

Bug:  763545 
TBR: mthiesse@chromium.org
Change-Id: Ieaa73a44d429d438d27f2b3ddaf4ac9d4c918948
Reviewed-on: https://chromium-review.googlesource.com/658924
Reviewed-by: Jinsuk Kim <jinsukkim@chromium.org>
Commit-Queue: Jinsuk Kim <jinsukkim@chromium.org>
Cr-Commit-Position: refs/heads/master@{#500819}
[modify] https://crrev.com/93edb8ef2b37b4157b5efd27f543b20c07af725e/chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShellImpl.java

 Issue 763628  has been merged into this issue.

verified in 63.0.3223.7