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}
Committed: https://chromium.googlesource.com/chromium/src/+/db2df0adddb5ab717ecbdc1c57e1e7aa958908da

[bokan, 2017-01-06 15:55:07]

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
==========

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
==========

[bokan, 2017-01-06 15:55:07]

bokan@chromium.org changed reviewers:
+ rune@opera.com

[bokan, 2017-01-06 15:57:05]

Hey Rune, I took a deeper look into this and I think your original fix is the
right one. In Autoresize the order of resizes is flipped. Normally we resize the
WebView which resizes the VisualViewport and then the layout size. In
autoresize, we resize the layout size and then the WebView. This means that the
VisualViewport might be "behind" in terms of size, but this shouldn't be a
problem on desktop which is where its used. I've added a test, ptal.

[rune, 2017-01-06 18:36:01]

lgtm

[bokan, 2017-01-06 18:36:22]

The CQ bit was checked by bokan@chromium.org

[commit-bot: I haz the power, 2017-01-06 18:36:58]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-01-06 21:05:37]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1483727782522720, "parent_rev":
"e6fef8190db76bbc5e9716d46296bfda636fad7f", "commit_rev":
"db2df0adddb5ab717ecbdc1c57e1e7aa958908da"}

[commit-bot: I haz the power, 2017-01-06 21:06:09]

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
==========

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}
Committed:
https://chromium.googlesource.com/chromium/src/+/db2df0adddb5ab717ecbdc1c57e1...
==========

[commit-bot: I haz the power, 2017-01-06 21:06:11]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/db2df0adddb5ab717ecbdc1c57e1...