Shape Detection: Implement FaceDetection on Mac as out-of-process service

This CL implements FaceDetection in //services/shape_detection. The Browser
forwards requests from the Renderer process to a Utility process, which detects
faces using Mac native CoreImage library and returns detection result.

DESIGN_DOC=http://tinyurl.com/shape-detection-in-chromium
BUG=659139
TEST=content/browser/shapedetection/shapedetection_browsertest.cc
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_site_isolation

Review-Url: https://codereview.chromium.org/2528743002
Cr-Commit-Position: refs/heads/master@{#445942}
24 files changed