Re-land "Replace requirePageReconstruction with setCustomUserAgent"

Re-land "Replace requirePageReconstruction with setCustomUserAgent"

This CL re-lands the "Replace requirePageReconstruction with
setCustomUserAgent" CL.

The following is the original CL descriptions:

WKWebView provides a property: customUserAgent that we can use to
change the user agent associated with the web view, which means that we
don't have to requirePageConstruction anymore when user agent changes.

After applying this change, I observed that it's becoming significantly
faster to navigate between desktop and mobile pages during back and
forward navigations.

BUG=707368
Review-Url: https://codereview.chromium.org/2822003002
Cr-Commit-Position: refs/heads/master@{#465042}
Committed: https://chromium.googlesource.com/chromium/src/+/b1688d0107c311a09b0bfb03df0b81ab9b21afc0

[liaoyuke, 2017-04-17 20:40:09]

liaoyuke@chromium.org changed reviewers:
+ eugenebut@chromium.org, kkhorimoto@chromium.org

[liaoyuke, 2017-04-17 20:40:09]

Hey Eugene, Kurt,

PTAL.

Here is what went wrong:

In CRWWebCOntroller, I replaced BOOL usesDesktopUserAgent with
web::UserAgentType userAgentType, and the returned user agent type is eventually
fed to web::GetWebClient()->GetUserAgent(user_agent_type)), which has a DCHECK
that user_agent_type cannot be NONE, thus, crashes happen when UA type is NONE.

Thank you very much!

[kkhorimoto, 2017-04-17 20:48:18]

lgtm

[Eugene But (OOO till 7-30), 2017-04-17 21:22:08]

lgtm

[liaoyuke, 2017-04-17 21:29:09]

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

[commit-bot: I haz the power, 2017-04-17 21:29:30]

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, 2017-04-17 21:43:17]

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

[commit-bot: I haz the power, 2017-04-17 21:43:18]

Dry run: This issue passed the CQ dry run.

[liaoyuke, 2017-04-17 22:13:46]

The CQ bit was checked by liaoyuke@chromium.org

[commit-bot: I haz the power, 2017-04-17 22:14:16]

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, 2017-04-17 22:18:23]

CQ is committing da patch.

Bot data: {"patchset_id": 20001, "attempt_start_ts": 1492467226497230,
"parent_rev": "11b7a48b230e2d6fa29d5604cf2f7929acbc3b81", "commit_rev":
"b1688d0107c311a09b0bfb03df0b81ab9b21afc0"}

[commit-bot: I haz the power, 2017-04-17 22:18:34]

Description was changed from

==========
Re-land "Replace requirePageReconstruction with setCustomUserAgent"

This CL re-lands the "Replace requirePageReconstruction with
setCustomUserAgent" CL.

The following is the original CL descriptions:

WKWebView provides a property: customUserAgent that we can use to
change the user agent associated with the web view, which means that we
don't have to requirePageConstruction anymore when user agent changes.

After applying this change, I observed that it's becoming significantly
faster to navigate between desktop and mobile pages during back and
forward navigations.

BUG=707368
==========

to

==========
Re-land "Replace requirePageReconstruction with setCustomUserAgent"

This CL re-lands the "Replace requirePageReconstruction with
setCustomUserAgent" CL.

The following is the original CL descriptions:

WKWebView provides a property: customUserAgent that we can use to
change the user agent associated with the web view, which means that we
don't have to requirePageConstruction anymore when user agent changes.

After applying this change, I observed that it's becoming significantly
faster to navigate between desktop and mobile pages during back and
forward navigations.

BUG=707368

Review-Url: https://codereview.chromium.org/2822003002
Cr-Commit-Position: refs/heads/master@{#465042}
Committed:
https://chromium.googlesource.com/chromium/src/+/b1688d0107c311a09b0bfb03df0b...
==========

[commit-bot: I haz the power, 2017-04-17 22:18:35]

Committed patchset #2 (id:20001) as
https://chromium.googlesource.com/chromium/src/+/b1688d0107c311a09b0bfb03df0b...