When page translation state is updated, just ask the toolbar to update, don't

When page translation state is updated, just ask the toolbar to update, don't
also ask it to restore saved state.

This eliminates the BrowserContentTranslateDriverObserver class in favor of just
implementing this on Browser directly as various other such observer
implementations do -- allowing the code to call the UpdateToolbar() method
instead of BrowserWindow::UpdateToolbar(), whose correct use is slightly less
clear.

BUG=459445
TEST=See steps on bug comment 22.  In step 1, be sure to restart Chrome after changing the language, and then set Chrome to prompt to translate pages in English.

Committed: https://crrev.com/cc29d20ef40d7b3d54e7ffbe9ba035d1a0c71ae1
Cr-Commit-Position: refs/heads/master@{#317993}

[Peter Kasting, 2015-02-24 02:25:18]

pkasting@chromium.org changed reviewers:
+ hajimehoshi@chromium.org

[hajimehoshi, 2015-02-24 05:07:34]

lgtm, thanks

[Peter Kasting, 2015-02-25 06:01:21]

The CQ bit was checked by pkasting@chromium.org

[commit-bot: I haz the power, 2015-02-25 06:01:48]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/949653003/1

[commit-bot: I haz the power, 2015-02-25 06:06:03]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-02-25 06:07:08]

Patchset 1 (id:??) landed as
https://crrev.com/cc29d20ef40d7b3d54e7ffbe9ba035d1a0c71ae1
Cr-Commit-Position: refs/heads/master@{#317993}