Remove web/{android, gtk, win}

The {android, gtk, win} directories contain only WebInputEventFactory.cpp.
We can just move these files to web/ with files renamed as WebInputEventFactoryAndroid.cpp,
WebInputEventFactoryGtk.cpp, WebInputEventFactoryWin.cpp respectively and remove the dir.
Moved the WebInputEventFactory.mm also to web/ as WebInputEventFactoryMac.mm but since web/mac/
still contains one more file, retained the dir. I will be removing it as part of another CL.

Uploading corrected change.
Original CL - http://crrev.com/27462002/
Revert CL - http://crrev.com/27532002/
Revert Reason - Aura builds failing.

BUG=None

TEST=None;no behavior changes;

Review URL: https://codereview.chromium.org/26247009

git-svn-id: svn://svn.chromium.org/blink/trunk@160060 bbb929c8-8fbe-4397-9dbb-9b2b20218538