Fix tooltips for Chrome OS shelf overflow icons.

Fix tooltips for Chrome OS shelf overflow icons.

Fixes a regression from https://codereview.chromium.org/1816753002
Add OverflowBubbleView's ShelfView after creating the bubble widget.
(ShelfTooltipManager init requires the widget to exist first)

BUG=601880
TEST=Chrome OS shelf overflow bubble shows tooltips.
R=sky@chromium.org

Review URL: https://codereview.chromium.org/1875033004

Cr-Commit-Position: refs/heads/master@{#386471}
(cherry picked from commit 01b843768f112912493d5a2510ecd6e09b0ed7bf)

Committed: https://chromium.googlesource.com/chromium/src/+/d1efceaa570b35862ecec60eaca67090fa3a1ade

[msw, 2016-04-14 18:54:06]

Description was changed from

==========
Fix tooltips for Chrome OS shelf overflow icons.

Fixes a regression from https://codereview.chromium.org/1816753002
Add OverflowBubbleView's ShelfView after creating the bubble widget.
(ShelfTooltipManager init requires the widget to exist first)

BUG=601880
TEST=Chrome OS shelf overflow bubble shows tooltips.
R=sky@chromium.org

Review URL: https://codereview.chromium.org/1875033004

Cr-Commit-Position: refs/heads/master@{#386471}
(cherry picked from commit 01b843768f112912493d5a2510ecd6e09b0ed7bf)
==========

to

==========
Fix tooltips for Chrome OS shelf overflow icons.

Fixes a regression from https://codereview.chromium.org/1816753002
Add OverflowBubbleView's ShelfView after creating the bubble widget.
(ShelfTooltipManager init requires the widget to exist first)

BUG=601880
TEST=Chrome OS shelf overflow bubble shows tooltips.
R=sky@chromium.org

Review URL: https://codereview.chromium.org/1875033004

Cr-Commit-Position: refs/heads/master@{#386471}
(cherry picked from commit 01b843768f112912493d5a2510ecd6e09b0ed7bf)

Committed:
https://chromium.googlesource.com/chromium/src/+/d1efceaa570b35862ecec60eaca6...
==========

[msw, 2016-04-14 18:54:08]

Committed patchset #1 (id:1) manually as
d1efceaa570b35862ecec60eaca67090fa3a1ade.