Remove StartPageView from being a AppListViewDelegateObserver

Remove StartPageView from being a AppListViewDelegateObserver

It observes OnProfilesChanged, but the set of profiles changing doesn't
affect the start page. However, it probably once helped avoid crashes
when deleting profiles since the AppListViewDelegate would hold on to
the Profile* until the app list was shown again. But that was fixed in
http://crrev.com/291852 (now AppListServiceImpl::DestroyAppList() will
reliably tear down the AppListView if the profile is destroyed, without
having to wait for a ShowAppList().

When regular profile switching occurs (i.e. not when the profile is
being destroyed), the profile currently being used by the
StartPageView is also replaced. That is handled by
AppListMainView::ModelChanged() calling into
ContentsView::InitNamedPages() which makes an entirely new
StartPageView().

BUG=403647
Committed: https://crrev.com/d6828ed750604b5914fa2cc26a739783efa0159b
Cr-Commit-Position: refs/heads/master@{#296175}

[tapted, 2014-09-23 06:29:18]

tapted@chromium.org changed reviewers:
+ calamity@chromium.org

[tapted, 2014-09-23 06:35:27]

for calamity. Pretty sure this is right....

[calamity, 2014-09-23 08:06:11]

lgtm. I think the beginning of the second paragraph has a word missing.

[tapted, 2014-09-23 13:32:17]

On 2014/09/23 08:06:11, calamity wrote:
> lgtm. I think the beginning of the second paragraph has a word missing.

Clarified it a bit:->

When regular profile switching occurs (i.e. not when the profile is
being destroyed), the profile currently being used by the
StartPageView is also replaced. That is handled by
AppListMainView::ModelChanged() calling into
ContentsView::InitNamedPages() which makes an entirely new
StartPageView().

[tapted, 2014-09-23 13:32:26]

The CQ bit was checked by tapted@chromium.org

[commit-bot: I haz the power, 2014-09-23 13:33:36]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/589333002/20001

[commit-bot: I haz the power, 2014-09-23 13:38:18]

Committed patchset #2 (id:20001) as 076150bcba691501962046450830327de7eaf1fb

[commit-bot: I haz the power, 2014-09-23 13:38:55]

Patchset 2 (id:??) landed as
https://crrev.com/d6828ed750604b5914fa2cc26a739783efa0159b
Cr-Commit-Position: refs/heads/master@{#296175}