athena: Add support for fling-scroll in overview mode.

athena: Add support for fling-scroll in overview mode.

Install an animation-observer in the compositor when a fling happens, and use a
FlingCurve (which implements the same fling-curve used for fling-scrolling
web-pages) to progress the fling at each animation step in the compositor.

BUG=398117
R=mukai@chromium.org, sky@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=287783

[sadrul, 2014-08-05 17:34:47]

sky@ for the addition of fling_curve in ui/events/ (it could live in any place,
since it doesn't have any dependency other than gfx, but events_base seems like
the better home for it)

oshima@ for athena/ changes.

[sky, 2014-08-05 17:53:37]

LGTM

https://codereview.chromium.org/436213002/diff/80001/ui/events/fling_curve.h
File ui/events/fling_curve.h (right):

https://codereview.chromium.org/436213002/diff/80001/ui/events/fling_curve.h#...
ui/events/fling_curve.h:5: #ifndef UI_EVENTS_FLING_CURVE_H_
As this is gesture related would it make sense to move this to
ui/events/gestures?

https://codereview.chromium.org/436213002/diff/80001/ui/events/fling_curve.h#...
ui/events/fling_curve.h:15: class EVENTS_BASE_EXPORT FlingCurve {
Add a description.

https://codereview.chromium.org/436213002/diff/80001/ui/events/fling_curve.h#...
ui/events/fling_curve.h:21: base::TimeTicks creation_time() const { return
start_timestamp_; }
nit: style guide says getter and field should match. So, either name this
start_timestamp() or rename start_timestamp_ to creation_time_.

https://codereview.chromium.org/436213002/diff/80001/ui/events/fling_curve.h#...
ui/events/fling_curve.h:28: base::TimeTicks start_timestamp_;
const?

[sadrul, 2014-08-05 18:09:06]

https://codereview.chromium.org/436213002/diff/80001/ui/events/fling_curve.h
File ui/events/fling_curve.h (right):

https://codereview.chromium.org/436213002/diff/80001/ui/events/fling_curve.h#...
ui/events/fling_curve.h:5: #ifndef UI_EVENTS_FLING_CURVE_H_
On 2014/08/05 17:53:36, sky wrote:
> As this is gesture related would it make sense to move this to
> ui/events/gestures?

Yep. Done.

https://codereview.chromium.org/436213002/diff/80001/ui/events/fling_curve.h#...
ui/events/fling_curve.h:15: class EVENTS_BASE_EXPORT FlingCurve {
On 2014/08/05 17:53:36, sky wrote:
> Add a description.

Done.

https://codereview.chromium.org/436213002/diff/80001/ui/events/fling_curve.h#...
ui/events/fling_curve.h:21: base::TimeTicks creation_time() const { return
start_timestamp_; }
On 2014/08/05 17:53:37, sky wrote:
> nit: style guide says getter and field should match. So, either name this
> start_timestamp() or rename start_timestamp_ to creation_time_.

Done (changed to start_timestamp()).

https://codereview.chromium.org/436213002/diff/80001/ui/events/fling_curve.h#...
ui/events/fling_curve.h:28: base::TimeTicks start_timestamp_;
On 2014/08/05 17:53:37, sky wrote:
> const?

Done.

[Jun Mukai, 2014-08-06 05:31:39]

lgtm

In addition to comments around IsZero, I'm a bit curious about where these
functions and constants come from (sorry, I'm not familiar with gestures and
these functions).

https://codereview.chromium.org/436213002/diff/100001/athena/wm/window_overvi...
File athena/wm/window_overview_mode.cc (right):

https://codereview.chromium.org/436213002/diff/100001/athena/wm/window_overvi...
athena/wm/window_overview_mode.cc:359: if (scroll.IsZero()) {
Vector2dF::IsZero() simply checks if both x and y equal to 0. Is this a good
method in this context?  Does scroll become 0 eventually?  Might be better to
check if y() is small enough (less than 0.001f for example).

https://codereview.chromium.org/436213002/diff/100001/ui/events/gestures/flin...
File ui/events/gestures/fling_curve_unittest.cc (right):

https://codereview.chromium.org/436213002/diff/100001/ui/events/gestures/flin...
ui/events/gestures/fling_curve_unittest.cc:12: TEST(FlingCurveTest, Basic) {
Related to my comment on WindowOverviewMode, it might be better to add a test
case which verifies if scroll.IsZero() will be satisfied when enough amount of
time has passed.

[sadrul, 2014-08-06 11:53:50]

> In addition to comments around IsZero, I'm a bit curious about where these
> functions and constants come from (sorry, I'm not familiar with gestures and
> these functions).

The constants come from UX experiments (thanks to rjkroege@/wjmaclean@). We use
this in renderer_preferences too.

https://codereview.chromium.org/436213002/diff/100001/athena/wm/window_overvi...
File athena/wm/window_overview_mode.cc (right):

https://codereview.chromium.org/436213002/diff/100001/athena/wm/window_overvi...
athena/wm/window_overview_mode.cc:359: if (scroll.IsZero()) {
On 2014/08/06 05:31:39, Jun Mukai wrote:
> Vector2dF::IsZero() simply checks if both x and y equal to 0. Is this a good
> method in this context?  Does scroll become 0 eventually?

scroll eventually becomes 0, yes. I have added a test case for this.

>  Might be better to
> check if y() is small enough (less than 0.001f for example).

https://codereview.chromium.org/436213002/diff/100001/ui/events/gestures/flin...
File ui/events/gestures/fling_curve_unittest.cc (right):

https://codereview.chromium.org/436213002/diff/100001/ui/events/gestures/flin...
ui/events/gestures/fling_curve_unittest.cc:12: TEST(FlingCurveTest, Basic) {
On 2014/08/06 05:31:39, Jun Mukai wrote:
> Related to my comment on WindowOverviewMode, it might be better to add a test
> case which verifies if scroll.IsZero() will be satisfied when enough amount of
> time has passed.

Done.

[sadrul, 2014-08-06 16:38:53]

Committed patchset #6 manually as 287783 (presubmit successful).