Added a views::test::TestInkDropAnimationObserverHelper

Added a views::test::TestInkDropAnimationObserverHelper

This change is a foundation for a follow-up CL that will be adding an
InkDropHoverObserver and a TestInkDropHoverObserver. This change will allow
code re-use between the InkDropHoverObserver/InkDropAnimationObserver and
TestInkDropHoverObserver/TestInkDropAnimationObserver classes.

BUG=604415
Review URL: https://codereview.chromium.org/1896953003

Cr-Commit-Position: refs/heads/master@{#388923}
(cherry picked from commit 0cf6c96f36bd9a5a6bbfebb13285d5166f193881)

Committed: https://chromium.googlesource.com/chromium/src/+/320158c73cd21e96d4ddd85ca18776505e766708

[bruthig, 2016-05-03 19:19:44]

Description was changed from

==========
Added a views::test::TestInkDropAnimationObserverHelper

This change is a foundation for a follow-up CL that will be adding an
InkDropHoverObserver and a TestInkDropHoverObserver. This change will allow
code re-use between the InkDropHoverObserver/InkDropAnimationObserver and
TestInkDropHoverObserver/TestInkDropAnimationObserver classes.

BUG=604415

Review URL: https://codereview.chromium.org/1896953003

Cr-Commit-Position: refs/heads/master@{#388923}
(cherry picked from commit 0cf6c96f36bd9a5a6bbfebb13285d5166f193881)
==========

to

==========
Added a views::test::TestInkDropAnimationObserverHelper

This change is a foundation for a follow-up CL that will be adding an
InkDropHoverObserver and a TestInkDropHoverObserver. This change will allow
code re-use between the InkDropHoverObserver/InkDropAnimationObserver and
TestInkDropHoverObserver/TestInkDropAnimationObserver classes.

BUG=604415

Review URL: https://codereview.chromium.org/1896953003

Cr-Commit-Position: refs/heads/master@{#388923}
(cherry picked from commit 0cf6c96f36bd9a5a6bbfebb13285d5166f193881)

Committed:
https://chromium.googlesource.com/chromium/src/+/320158c73cd21e96d4ddd85ca187...
==========

[bruthig, 2016-05-03 19:19:46]

Committed patchset #1 (id:1) manually as
320158c73cd21e96d4ddd85ca18776505e766708.