Append variation headers when fetching snippets.

Append variation headers when fetching snippets.

Since we are directly using URLFetcher, this is not done automatically.
In order to propagate experiments to Google servers, this call needs to
be done manually.

Snippets are not enabled for incognito NTPs, so we pass false for
|incognito|.

BUG=629493
Review-Url: https://codereview.chromium.org/2164593002
Cr-Commit-Position: refs/heads/master@{#406269}
(cherry picked from commit 630a991e73d67ae1162d9b64e22308f9c9df29ba)

Committed: https://chromium.googlesource.com/chromium/src/+/fa48aa6bb99092a7e4d5f1ca6922f8d54086c72e

[Marc Treib, 2016-07-20 12:11:46]

Description was changed from

==========
Append variation headers when fetching snippets.

Since we are directly using URLFetcher, this is not done automatically.
In order to propagate experiments to Google servers, this call needs to
be done manually.

Snippets are not enabled for incognito NTPs, so we pass false for
|incognito|.

BUG=629493

Review-Url: https://codereview.chromium.org/2164593002
Cr-Commit-Position: refs/heads/master@{#406269}
(cherry picked from commit 630a991e73d67ae1162d9b64e22308f9c9df29ba)
==========

to

==========
Append variation headers when fetching snippets.

Since we are directly using URLFetcher, this is not done automatically.
In order to propagate experiments to Google servers, this call needs to
be done manually.

Snippets are not enabled for incognito NTPs, so we pass false for
|incognito|.

BUG=629493

Review-Url: https://codereview.chromium.org/2164593002
Cr-Commit-Position: refs/heads/master@{#406269}
(cherry picked from commit 630a991e73d67ae1162d9b64e22308f9c9df29ba)

Committed:
https://chromium.googlesource.com/chromium/src/+/fa48aa6bb99092a7e4d5f1ca6922...
==========

[Marc Treib, 2016-07-20 12:11:47]

Committed patchset #1 (id:1) manually as
fa48aa6bb99092a7e4d5f1ca6922f8d54086c72e (tree was closed).