Bug 937336 - Remove where possible explicit frame switching

Replacing explicit frame switching calls to use the encapsulated switch_to_displayed_app method
Bug 949062 - Update test_music.py file to be more explicit about failing to play the mp3 file
Bug 949366 - [Download Manager] Stopped and failed downloads are displayed as canceled
Bug 949395 - [Download Manager] Downloading progress bar is not displayed after restart a stopped download
Bug 952423 - [Download Manager] Error message should be No memory card found (consistency with existing strings)
Bug 937096 - The ringtone name does not appear in sounds settings.
Bug 951252 - Remove warning on undefined role when checking hidden status

There is too much output because in the default case, role is undefined.
As per bug 951252, let's disable the output.
Merge pull request #14888 from crdlc/bug-952423

Bug 952423 - [Download Manager] Error message should be No memory card f...
Merge pull request #14763 from acperez/bug-937096

Bug 937096 - The ringtone name does not appear in sounds settings.
Merge pull request #14885 from crdlc/bug-949395

Bug 949395 - [Download Manager] Downloading progress bar is not displaye...
[Bug 952449] New: [Messages] Fix the un-fixed issues reported in the review of Bug #907740
Merge pull request #14857 from crdlc/bug-949366

Bug 949366 - [Download Manager] Stopped and failed downloads are display...
Merge pull request #14795 from lissyx/bug951252

Bug 951252 - Remove warning on undefined role when checking hidden status r=vingtetun
Merge pull request #14853 from AndreiH/bug_949062

Bug 949062 - Update test_music.py file to be more explicit about failing...
Bug 797661 - Hotspot should have random password
Merge pull request #14894 from jmcanterafonseca/bug_952449

[Bug 952449] [Messages] Fix the un-fixed issues reported in the rev...
Merge pull request #14611 from arroway/bug-797661

Bug 797661 - Hotspot should have random password, r=kaze
Bug 952455 - [Contacts][Bluetooth] "Export to Bluetooth" message blocks the Contacts app and leaves it unusable
Merge pull request #14849 from bobsilverberg/switch_to_displayed_app

Bug 937336 - Remove where possible explicit frame switching
Merge pull request #14897 from gtorodelvalle/contacts-bug-952455-export-to-bluetooth

Bug 952455 - [Contacts][Bluetooth] "Export to Bluetooth" message blocks the Contacts app and leaves it unusable