Apply user agent exactly once for requests from Blink.

Apply user agent exactly once for requests from Blink.

For most regular fetches, we apply the user agent twice:
- addAdditionalRequestHeaders
- prepareRequest

This patch changes FrameLoader::applyUserAgent to
FrameLoader::applyUserAgentIfNeeded which first checks if the user agent
is set. This avoids going to the embedder to calculate the override twice.

BUG=348655
Committed: https://crrev.com/068d63ed251f23d4d3cbd06c5d702abae09c7ce9
Cr-Commit-Position: refs/heads/master@{#427180}

[Charlie Harrison, 2016-10-24 15:26:45]

The CQ bit was checked by csharrison@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-10-24 15:27:09]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-10-24 16:46:35]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-10-24 16:46:36]

Dry run: Try jobs failed on following builders:
  android_clang_dbg_recipe on master.tryserver.chromium.android (JOB_FAILED,
https://build.chromium.org/p/tryserver.chromium.android/builders/android_clan...)

[Charlie Harrison, 2016-10-24 17:24:53]

csharrison@chromium.org changed reviewers:
+ japhet@chromium.org

[Charlie Harrison, 2016-10-24 17:24:54]

japhet, PTAL?

[Nate Chapin, 2016-10-24 17:26:46]

LGTM I guess, but do we really need the user agent set in both those functions?
Can we remove one of those calls?

[Charlie Harrison, 2016-10-24 17:36:50]

On 2016/10/24 17:26:46, Nate Chapin wrote:
> LGTM I guess, but do we really need the user agent set in both those
functions?
> Can we remove one of those calls?

I can't remove it from addAdditionalRequestHeaders, because PingLoader needs it
(we'd need something like applyUserAgent to FetchContext).

I could remove it from prepareRequest and just add it specifically for redirects
in FrameFetchContext::dispatchWillSendRequest. That's arguably a better solution
than this one, so I'll try it.

[Charlie Harrison, 2016-10-24 17:52:34]

The CQ bit was checked by csharrison@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-10-24 17:53:15]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[Charlie Harrison, 2016-10-24 17:53:38]

Actually, pings end up calling prepareRequest via willStartLoadingResource, so
let's try removing it from addAdditionalRequestHeaders.

Current PS does that, hopefully bots agree with me :)

[commit-bot: I haz the power, 2016-10-24 19:57:32]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-10-24 19:57:33]

Dry run: Try jobs failed on following builders:
  win_chromium_rel_ng on master.tryserver.chromium.win (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_rel_...)

[Charlie Harrison, 2016-10-24 20:00:09]

On 2016/10/24 17:53:38, Charlie Harrison wrote:
> Actually, pings end up calling prepareRequest via willStartLoadingResource, so
> let's try removing it from addAdditionalRequestHeaders.
> 
> Current PS does that, hopefully bots agree with me :)

Bots seem fine (ish). The failures look unrelated. Mind taking another pass?

[Nate Chapin, 2016-10-24 20:08:33]

LGTM, thanks!

[Charlie Harrison, 2016-10-24 20:10:05]

The CQ bit was checked by csharrison@chromium.org

[commit-bot: I haz the power, 2016-10-24 20:10:59]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-10-24 22:08:01]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-10-24 22:08:03]

Try jobs failed on following builders:
  android_arm64_dbg_recipe on master.tryserver.chromium.android (JOB_FAILED,
https://build.chromium.org/p/tryserver.chromium.android/builders/android_arm6...)

[Charlie Harrison, 2016-10-24 22:08:31]

The CQ bit was checked by csharrison@chromium.org

[commit-bot: I haz the power, 2016-10-24 22:09:09]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-10-24 23:37:27]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-10-24 23:38:55]

Description was changed from

==========
Apply user agent exactly once for requests from Blink.

For most regular fetches, we apply the user agent twice:
- addAdditionalRequestHeaders
- prepareRequest

This patch changes FrameLoader::applyUserAgent to
FrameLoader::applyUserAgentIfNeeded which first checks if the user agent
is set. This avoids going to the embedder to calculate the override twice.

BUG=348655
==========

to

==========
Apply user agent exactly once for requests from Blink.

For most regular fetches, we apply the user agent twice:
- addAdditionalRequestHeaders
- prepareRequest

This patch changes FrameLoader::applyUserAgent to
FrameLoader::applyUserAgentIfNeeded which first checks if the user agent
is set. This avoids going to the embedder to calculate the override twice.

BUG=348655

Committed: https://crrev.com/068d63ed251f23d4d3cbd06c5d702abae09c7ce9
Cr-Commit-Position: refs/heads/master@{#427180}
==========

[commit-bot: I haz the power, 2016-10-24 23:38:59]

Patchset 2 (id:??) landed as
https://crrev.com/068d63ed251f23d4d3cbd06c5d702abae09c7ce9
Cr-Commit-Position: refs/heads/master@{#427180}