[Cronet] Add new API methods before removing old ones

[Cronet] Add new API methods before removing old ones

To allow embedders to update to the new API piecemeal, rather than
forcing an all-at-once update:
1. Allow mocking of UrlRequest.Builder by making non-final. This
   allows embedders to prepare for removal of CronetEngine.createRequest().
2. Add CronetEngine.newUrlRequestBuilder()

R=kapishnikov
BUG=654432
Review-Url: https://codereview.chromium.org/2402753002
Cr-Commit-Position: refs/heads/master@{#424154}
(cherry picked from commit 4480e95462fa0a4a59f7ba517a5fde5262aa8801)

Committed: https://chromium.googlesource.com/chromium/src/+/94b92e7ee8b2a5a266ba40298abb801119632fd8

[pauljensen, 2016-10-10 15:56:50]

Description was changed from

==========
[Cronet] Add new API methods before removing old ones

To allow embedders to update to the new API piecemeal, rather than
forcing an all-at-once update:
1. Allow mocking of UrlRequest.Builder by making non-final. This
   allows embedders to prepare for removal of CronetEngine.createRequest().
2. Add CronetEngine.newUrlRequestBuilder()

R=kapishnikov
BUG=654432

Review-Url: https://codereview.chromium.org/2402753002
Cr-Commit-Position: refs/heads/master@{#424154}
(cherry picked from commit 4480e95462fa0a4a59f7ba517a5fde5262aa8801)
==========

to

==========
[Cronet] Add new API methods before removing old ones

To allow embedders to update to the new API piecemeal, rather than
forcing an all-at-once update:
1. Allow mocking of UrlRequest.Builder by making non-final. This
   allows embedders to prepare for removal of CronetEngine.createRequest().
2. Add CronetEngine.newUrlRequestBuilder()

R=kapishnikov
BUG=654432

Review-Url: https://codereview.chromium.org/2402753002
Cr-Commit-Position: refs/heads/master@{#424154}
(cherry picked from commit 4480e95462fa0a4a59f7ba517a5fde5262aa8801)

Committed:
https://chromium.googlesource.com/chromium/src/+/94b92e7ee8b2a5a266ba40298abb...
==========

[pauljensen, 2016-10-10 15:56:52]

Committed patchset #1 (id:1) manually as
94b92e7ee8b2a5a266ba40298abb801119632fd8.