Add a few items to ContextMenu.

Add a few items to ContextMenu.

This CL adds contextmenu_save_link_as to fullscreen tabs mode and
contextmenu_search_by_image to custom tabs mode of context menu.

BUG=550272
Committed: https://crrev.com/12aa65007fe22d29520d8858291e3bedff9c9887
Cr-Commit-Position: refs/heads/master@{#358095}

[aurimas (slooooooooow), 2015-11-05 17:26:14]

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

[commit-bot: I haz the power, 2015-11-05 17:27:03]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1434533002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1434533002/1

[aurimas (slooooooooow), 2015-11-05 17:27:28]

aurimas@chromium.org changed reviewers:
+ tedchoc@chromium.org

[aurimas (slooooooooow), 2015-11-05 17:27:29]

PTAL. Adjusting the context menus to rolfe's suggestions. See crbug.com/550272

[Ted C, 2015-11-05 17:28:30]

lgtm

[commit-bot: I haz the power, 2015-11-05 18:08:47]

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

[commit-bot: I haz the power, 2015-11-05 18:08:48]

Dry run: This issue passed the CQ dry run.

[aurimas (slooooooooow), 2015-11-05 18:33:16]

The CQ bit was checked by aurimas@chromium.org

[commit-bot: I haz the power, 2015-11-05 18:33:46]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1434533002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1434533002/1

[commit-bot: I haz the power, 2015-11-05 18:46:29]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-11-05 18:47:20]

Patchset 1 (id:??) landed as
https://crrev.com/12aa65007fe22d29520d8858291e3bedff9c9887
Cr-Commit-Position: refs/heads/master@{#358095}