Fix crash with viewport units when using auto resize mode.

Fix crash with viewport units when using auto resize mode.

This crash is caused because of a divide-by-zero when calculating viewport
units. The zero width visual viewport occurs because the WebView is responsible
for resizing the VisualViewport but the autoresize code resizes the FrameView.
This does eventually lead to resizing the WebView when a layout occurs and
calls though to WebView::layoutUpdated, however, until that happens the layout
will use the 0 value.

This isn't ever a problem since the calculation that's dividing by 0 is used to
adjust the browser controls to the minimum page scale but autoresize isn't ever
used on Android, which is the only platform that uses browser controls and a
non-1 minimum page scale.

BUG=667712
Review-Url: https://codereview.chromium.org/2616893004
Cr-Commit-Position: refs/heads/master@{#442048}
(cherry picked from commit db2df0adddb5ab717ecbdc1c57e1e7aa958908da)

Review-Url: https://codereview.chromium.org/2619173003 .
Cr-Commit-Position: refs/branch-heads/2924@{#700}
Cr-Branched-From: 3a87aecc31cd1ffe751dd72c04e5a96a1fc8108a-refs/heads/master@{#433059}
Committed: https://chromium.googlesource.com/chromium/src/+/14d6aa23de9ae621a6df2df9045c31d3d5a8cfae

[bokan, 2017-01-09 14:58:31]

Description was changed from

==========
Fix crash with viewport units when using auto resize mode.

This crash is caused because of a divide-by-zero when calculating viewport
units. The zero width visual viewport occurs because the WebView is responsible
for resizing the VisualViewport but the autoresize code resizes the FrameView.
This does eventually lead to resizing the WebView when a layout occurs and
calls though to WebView::layoutUpdated, however, until that happens the layout
will use the 0 value.

This isn't ever a problem since the calculation that's dividing by 0 is used to
adjust the browser controls to the minimum page scale but autoresize isn't ever
used on Android, which is the only platform that uses browser controls and a
non-1 minimum page scale.

BUG=667712

Review-Url: https://codereview.chromium.org/2616893004
Cr-Commit-Position: refs/heads/master@{#442048}
(cherry picked from commit db2df0adddb5ab717ecbdc1c57e1e7aa958908da)
==========

to

==========
Fix crash with viewport units when using auto resize mode.

This crash is caused because of a divide-by-zero when calculating viewport
units. The zero width visual viewport occurs because the WebView is responsible
for resizing the VisualViewport but the autoresize code resizes the FrameView.
This does eventually lead to resizing the WebView when a layout occurs and
calls though to WebView::layoutUpdated, however, until that happens the layout
will use the 0 value.

This isn't ever a problem since the calculation that's dividing by 0 is used to
adjust the browser controls to the minimum page scale but autoresize isn't ever
used on Android, which is the only platform that uses browser controls and a
non-1 minimum page scale.

BUG=667712

Review-Url: https://codereview.chromium.org/2616893004
Cr-Commit-Position: refs/heads/master@{#442048}
(cherry picked from commit db2df0adddb5ab717ecbdc1c57e1e7aa958908da)

Review-Url: https://codereview.chromium.org/2619173003 .
Cr-Commit-Position: refs/branch-heads/2924@{#700}
Cr-Branched-From:
3a87aecc31cd1ffe751dd72c04e5a96a1fc8108a-refs/heads/master@{#433059}
Committed:
https://chromium.googlesource.com/chromium/src/+/14d6aa23de9ae621a6df2df9045c...
==========

[bokan, 2017-01-09 14:58:32]

Committed patchset #1 (id:1) manually as
14d6aa23de9ae621a6df2df9045c31d3d5a8cfae.