[chromium] Provide WebKit API interface for platform gesture curves
https://bugs.webkit.org/show_bug.cgi?id=100675

Reviewed by James Robinson.

Define interfaces to permit the Chromium embedder to provide its own
implementation of a gesture animation curve and add an entry point
to Platform.h that permits WebKit to obtain an instance of an embedder-
provided gesture curve.

No tests needed in this CL: only interfaces are being added.

* Platform.gypi:
* chromium/public/Platform.h:
(WebKit):
(Platform):
(WebKit::Platform::createFlingAnimationCurve):
* chromium/public/WebGestureCurve.h: Added.
(WebKit):
(WebGestureCurve):
(WebKit::WebGestureCurve::~WebGestureCurve):
* chromium/public/WebGestureCurveTarget.h: Added.
(WebKit):
(WebGestureCurveTarget):
(WebKit::WebGestureCurveTarget::~WebGestureCurveTarget):
* chromium/src/WebActiveGestureAnimation.cpp: Added.
(WebKit):
(WebKit::WebActiveGestureAnimation::createAtAnimationStart):
(WebKit::WebActiveGestureAnimation::createWithTimeOffset):
(WebKit::WebActiveGestureAnimation::~WebActiveGestureAnimation):
(WebKit::WebActiveGestureAnimation::WebActiveGestureAnimation):
(WebKit::WebActiveGestureAnimation::animate):
* chromium/src/WebActiveGestureAnimation.h: Added.
(WebKit):
(WebActiveGestureAnimation):


git-svn-id: https://svn.webkit.org/repository/webkit/trunk/Source/Platform/chromium/public@133203 268f45cc-cd09-0410-ab3c-d52691b4dbfc