Fix jank caused by infobars appearing.

Fix jank caused by infobars appearing.

When the InfoBarContainer is first attached to the window,
View.initialAwakenScrollBars() is called on it. Even though the scrollbars
aren't visible, this schedules a delayed runnable to fade out the scrollbars
1.2 seconds later. This delayed runnable (View$ScrollabilityCache) then calls
View.invalidate() repeatedly as it fades out the (already invisible) scrollbar,
which pauses scroll updates and touch event handling for 10 to 15 frames.

This CL disables the scrollbars on the InfoBarContainer, except in the rare
case that the container is actually scrollable (i.e. when infobars take up the
entire screen). In that case, page jank doesn't matter since the user can't
even see the webpage!

BUG=407149
NOTRY=true

Committed: https://crrev.com/7cca8293771e68026262d05cd7c13620d8a79a3f
Cr-Commit-Position: refs/heads/master@{#295849}

[newt (away), 2014-09-20 01:00:19]

newt@chromium.org changed reviewers:
+ dfalcantara@chromium.org, jdduke@chromium.org

[newt (away), 2014-09-20 01:00:19]

PTAL

[gone, 2014-09-20 01:21:09]

lgtm

[newt (away), 2014-09-20 01:30:07]

The CQ bit was checked by newt@chromium.org

[commit-bot: I haz the power, 2014-09-20 01:31:37]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/588843002/1

[commit-bot: I haz the power, 2014-09-20 01:31:37]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/588843002/1

[newt (away), 2014-09-20 02:37:06]

The CQ bit was unchecked by newt@chromium.org

[newt (away), 2014-09-20 02:37:17]

The CQ bit was checked by newt@chromium.org

[commit-bot: I haz the power, 2014-09-20 02:37:27]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/588843002/1

[commit-bot: I haz the power, 2014-09-20 02:38:26]

Committed patchset #1 (id:1) as d79f915472ca973851ea184ad32dc4191fccbfd1

[commit-bot: I haz the power, 2014-09-20 02:39:01]

Patchset 1 (id:??) landed as
https://crrev.com/7cca8293771e68026262d05cd7c13620d8a79a3f
Cr-Commit-Position: refs/heads/master@{#295849}

[jdduke (slow), 2014-09-20 02:54:37]

Yay, lgtm!