Splitting ChildProcessServiceImpl for basification.

Splitting ChildProcessServiceImpl with a delegate and moving the
content specific logic to a content implementation class.
ChildProcessServiceImpl takes care of initializing the command line and
registering file descriptors. This class will be next moved to base.
The content specific behavior (using the custom linker, providing the
GPU surfaces to the renderer) is moved to the content implementation
of the delegate, ContentChildProcessServiceDelegate.

Bug: 702316
Change-Id: I357e2a81836a97cf53888ca3d7ec3b46e12c91a1
Reviewed-on: https://chromium-review.googlesource.com/526262
Reviewed-by: Ted Choc <tedchoc@chromium.org>
Reviewed-by: Jay Civelli <jcivelli@chromium.org>
Reviewed-by: Bo Liu <boliu@chromium.org>
Reviewed-by: Xi Han <hanxi@chromium.org>
Reviewed-by: Tao Bai <michaelbai@chromium.org>
Commit-Queue: Jay Civelli <jcivelli@chromium.org>
Cr-Commit-Position: refs/heads/master@{#481236}
14 files changed