GetDisplayForScreen cleanup

Doing the primary display check inside the GetDisplayForScreen function
so that the other utility functions can stop guessing about whether
the display they return is primary or not.

BUG=
R=Nico

Review URL: https://codereview.chromium.org/47073006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@232054 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 232054
Adjust the display logic for download destination option for CrOS multi-profile.

To support multi-profiles, the path to the default "Downloads" folder
is going to vary for each profile. We need to generalize the part that
assumed the fixed path "/home/chronos/user/Downloads", and this options
page is one of them.

Some context. The current directory structure looks like:
- /home/chronos/u-xxxxx/Downloads (the primary profile's directory)
- /home/chronos/u-yyyyy/Downloads (the secondary profile's directory)
- ...
- /home/chronos/user (hard link to /home/chronos/u-xxxxx)
and the "user" link points to the primary logged-in profile's directory.
Thus, depending on whether it is loaded as a primary profile or secondary
into a multi-profile session, "/home/chronos/user/Downloads" points to a
different entry. To avoid that, I'm now switching to use the
"/home/chronos/u-xxxxx/Downloads" path always.

BUG=309556

Review URL: https://codereview.chromium.org/50573005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@232055 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 232055
Move ExtensionSystem references out of ExtensionAppModelBuilder.

BUG=310376

Review URL: https://codereview.chromium.org/52143002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@232056 0039d316-1c4b-4281-b951-d872f2087c98
Collect UMAs (Modify*Lang) into TranslateUIDelegate

Renamed TranslateUIDelegate::Set*LanguageIndex to Update*LanguageIndex and have them include UMA callings.

BUG=312720
TEST=unit_tests --gtest_filter=TranslateBubbleViewTest.*

Review URL: https://codereview.chromium.org/52213002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@232057 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 232057