PlzNavigate: Expose blink to content enum type converters.

PlzNavigate: Expose blink to content enum type converters.

This is a spin-off of https://codereview.chromium.org/1294243004/
This exposes the helper functions converting enum types from a blink type to its
corresponding content type.

BUG=440463
Committed: https://crrev.com/f961204e71ecd50dbed4bb1eb8e45ee62ffaf69c
Cr-Commit-Position: refs/heads/master@{#348772}

[Fabrice (no longer in Chrome), 2015-09-07 16:59:46]

fdegans@chromium.org changed reviewers:
+ carlosk@chromium.org, clamy@chromium.org, horo@chromium.org,
kinuko@chromium.org, michaeln@chromium.org, nasko@chromium.org

[Fabrice (no longer in Chrome), 2015-09-07 16:59:47]

nasko: PTAL
others: FYI
This is a simple spin-off of https://codereview.chromium.org/1294243004/
I am preparing another CL to add the arguments to the NavigationParams structs
separately.

[clamy, 2015-09-14 19:52:08]

Thanks! Lgtm

[nasko, 2015-09-14 21:08:51]

LGTM

[Fabrice (no longer in Chrome), 2015-09-14 21:26:52]

The CQ bit was checked by fdegans@chromium.org

[commit-bot: I haz the power, 2015-09-14 21:29:29]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1317833005/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1317833005/1

[commit-bot: I haz the power, 2015-09-14 23:05:59]

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

[commit-bot: I haz the power, 2015-09-14 23:06:00]

Try jobs failed on following builders:
  win8_chromium_ng on tryserver.chromium.win (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.win/builders/win8_chromium_ng/...)

[Fabrice (no longer in Chrome), 2015-09-14 23:06:42]

The CQ bit was checked by fdegans@chromium.org

[commit-bot: I haz the power, 2015-09-14 23:08:02]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1317833005/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1317833005/1

[commit-bot: I haz the power, 2015-09-14 23:50:24]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-09-14 23:51:11]

Patchset 1 (id:??) landed as
https://crrev.com/f961204e71ecd50dbed4bb1eb8e45ee62ffaf69c
Cr-Commit-Position: refs/heads/master@{#348772}

[commit-bot: I haz the power, 2015-09-23 12:39:27]

Patchset 1 (id:??) landed as
https://crrev.com/f961204e71ecd50dbed4bb1eb8e45ee62ffaf69c
Cr-Commit-Position: refs/heads/master@{#348772}