Use ChromeBrowserStateManager instead of BrowserListIOS.

The BrowserListIOS was there as a parallel to BrowserList while the
code was forked and is now only of historical interest as all of its
methods can be implemented using ChromeBrowserStateManager.

The following rules were used when converting from BrowserListIOS to
ChromeBrowserStateManager:

- re-implement BrowserListIOS::GetLastActiveWithBrowserState in term
  of iterating over all ios::ChromeBrowserState registered with the
  ChromeBrowserStateManager, and then over the TabModels associated
  with those ios::ChromeBrowserState

- iteration over BrowserListIOS::begin()/BrowserListIOS::end() can be
  replaced by iterating over the list from GetLoadedBrowserState() and
  if off-the-record ios::ChromeBrowserState are wanted it, and for each
  of them iterating over the TabModels associated

- BrowserListIOS::IsOffTheRecordSessionActive is re-implemented as
  a free function implemented on top of ChromeBrowserStateManager using
  the same rules.

BUG=None

Review-Url: https://codereview.chromium.org/2615003002
Cr-Original-Commit-Position: refs/heads/master@{#443590}
Committed: https://chromium.googlesource.com/chromium/src/+/20f7270f96d194b98f3053a1f5035552cf758c2c
Review-Url: https://codereview.chromium.org/2615003002
Cr-Commit-Position: refs/heads/master@{#443900}
29 files changed