Replaced CursorLoader in PlatformDisplay with a ImageCursor

ImageCursor->SetDisplay() is called in Init() so that all cursors are loaded at
launch. This fixes the bug where the cursor image is positioned off to the left
in Chrome mash.

BUG=615861

Review-Url: https://codereview.chromium.org/2268563003
Cr-Commit-Position: refs/heads/master@{#439154}
5 files changed