Don't fade in overlay scrollbar when user interacting the content under scrollbar.

Don't fade in overlay scrollbar when user interacting the content under scrollbar.

The issue (crbug.com/719011) indicate that it is hard to interact with
the content under the the scrollbar because the scrollbar will fade in
while mouse moves in the hover fade in region of scrollbar.

In this patch, we prevent fade in overlay scrollbar when user mouse
down. 3 behaviors changed:

1. When mouse move in hover fade in region of scrollbar with mouse
   press, we don't trigger delay fade in.
2. When mouse down after a delay fade in triggered, cancel the delay
   fade in.
3. When mouse up in hover fade in region of scrollbar, trigger a delay
   fade in.

BUG=719011
CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel

Review-Url: https://codereview.chromium.org/2931703002
Cr-Original-Commit-Position: refs/heads/master@{#478733}
Review-Url: https://codereview.chromium.org/2957093003 .
Cr-Commit-Position: refs/branch-heads/3112@{#478}
Cr-Branched-From: b6460e24cf59f429d69de255538d0fc7a425ccf9-refs/heads/master@{#474897}
Committed: https://chromium.googlesource.com/chromium/src/+/ec0cede7db7fada94b0d69a44d7f0e6c138ee877

[bokan, 2017-06-27 15:21:38]

Description was changed from

==========
Don't fade in overlay scrollbar when user interacting the content under
scrollbar.

The issue (crbug.com/719011) indicate that it is hard to interact with
the content under the the scrollbar because the scrollbar will fade in
while mouse moves in the hover fade in region of scrollbar.

In this patch, we prevent fade in overlay scrollbar when user mouse
down. 3 behaviors changed:

1. When mouse move in hover fade in region of scrollbar with mouse
   press, we don't trigger delay fade in.
2. When mouse down after a delay fade in triggered, cancel the delay
   fade in.
3. When mouse up in hover fade in region of scrollbar, trigger a delay
   fade in.

BUG=719011
CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel

Review-Url: https://codereview.chromium.org/2931703002
Cr-Commit-Position: refs/heads/master@{#478733}
(cherry picked from commit ac6ccd29b4eaa1e056c0cd0656e2fad8aa624d42)
==========

to

==========
Don't fade in overlay scrollbar when user interacting the content under
scrollbar.

The issue (crbug.com/719011) indicate that it is hard to interact with
the content under the the scrollbar because the scrollbar will fade in
while mouse moves in the hover fade in region of scrollbar.

In this patch, we prevent fade in overlay scrollbar when user mouse
down. 3 behaviors changed:

1. When mouse move in hover fade in region of scrollbar with mouse
   press, we don't trigger delay fade in.
2. When mouse down after a delay fade in triggered, cancel the delay
   fade in.
3. When mouse up in hover fade in region of scrollbar, trigger a delay
   fade in.

BUG=719011
CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel

Review-Url: https://codereview.chromium.org/2931703002
Cr-Original-Commit-Position: refs/heads/master@{#478733}
Review-Url: https://codereview.chromium.org/2957093003 .
Cr-Commit-Position: refs/branch-heads/3112@{#478}
Cr-Branched-From:
b6460e24cf59f429d69de255538d0fc7a425ccf9-refs/heads/master@{#474897}
Committed:
https://chromium.googlesource.com/chromium/src/+/ec0cede7db7fada94b0d69a44d7f...
==========

[bokan, 2017-06-27 15:21:39]

Committed patchset #1 (id:1) manually as
ec0cede7db7fada94b0d69a44d7f0e6c138ee877.