[Chromium] gamepad changes to the public interface of Chromium port

[Chromium] gamepad changes to the public interface of Chromium port
https://bugs.webkit.org/show_bug.cgi?id=71518

Patch by Scott Graham <scottmg@chromium.org> on 2011-11-15
Reviewed by Darin Fisher.

Adds stubs for Chromium port, and defines shared memory structure to
be used between browser and WebKit.

Includes just the parts that touch the public interface so they can be
reviewed separately. See also:
https://bugs.webkit.org/show_bug.cgi?id=69451 and
http://codereview.chromium.org/8345027

* WebKit.gyp:
* public/WebGamepad.h: Added.
(WebKit::WebGamepad::WebGamepad):
* public/WebGamepads.h: Added.
(WebKit::WebGamepads::WebGamepads):
* public/WebKitPlatformSupport.h:
(WebKit::WebKitPlatformSupport::sampleGamepads):
* public/WebRuntimeFeatures.h:
* src/WebRuntimeFeatures.cpp:
(WebKit::WebRuntimeFeatures::enableGamepad):
(WebKit::WebRuntimeFeatures::isGamepadEnabled):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@100306 268f45cc-cd09-0410-ab3c-d52691b4dbfc