gfx: Add FrameTime and DisplayTime classes

gfx: Add FrameTime and DisplayTime classes

This patch replaces base::TimeTicks with gfx::FrameTime
for everything related to animations, scheduling, and
display times.

In a subsequent patch, DisplayTime will also be used
to indicate parts of code that need a timestamp that
should be aligned with the display's refresh phase.

FrameTime and DisplayTime both have methods that
start with "Unsafe", which will mark areas of code
that are potentially using an incorrect timestamp.

Further followups should remove calls to the Unsafe
methods so we can remove them.

BUG=311570

[brianderson, 2013-10-17 18:42:20]

https://codereview.chromium.org/26880010/diff/1/ui/gfx/frame_time.h
File ui/gfx/frame_time.h (right):

https://codereview.chromium.org/26880010/diff/1/ui/gfx/frame_time.h#newcode101
ui/gfx/frame_time.h:101: // If animations are using anything other than a
FrameTime, there
*there is something wrong.

[mithro-old, 2014-12-19 06:17:20]

You can close this issue now.

[mithro-old, 2015-04-02 04:35:12]

Hey Brian,

Can you close this CL?

Tim