New Google Picker UI polish and bug fixes

[seanh]

• [x] Fix the new Google Picker in non-Canvas LMS's

  Pull request: https://github.com/hypothesis/lms/pull/678

  The Select PDF from Google Drive button only seems to appear when I launch the app in Canvas but not when I launch it in Potemkin (and, I'm guessing, not in other non-Canvas LMS's like Moodle etc).

  Select PDF from Google Drive should always be shown -- it doesn't vary with the LMS or the application instance and there's nothing the user needs to do to enable it, it's just there all the time.

• [ ] Use the Canvas Picker's Allow file access dialog for the Google Picker as well

  When selecting a Canvas file, when the authorization popup window is open, the dialog behind it changes to a view that explains what the user needs to do and includes an Authorize button that re-raises the popup window if the user has lost it, and a Cancel button that closes the popup and goes back to the previous view. This Allow file access view is also handily reusable after the popup window has closed but the list files proxy API request failed for any reason (use clicked Cancel instead of Authorize, server's Canvas API request failed, ...):

  

  Can the Google Picker work in the same way? When the Google Picker authorization popup window is open show a Allow file access dialog (To select a file, you must authorize Hypothesis to access your files in Google Drive) with Cancel and Authorize buttons?

  Current Google Picker behaviour -- if you go back to the dialog while the popup window is still open, the dialog gives no indication of what is happening or what the user it trying to do, and no way to re-raise the popup window or to cancel:

  

• [ ] Replace the new Google Picker's error dialog with the Allow file access dialog

  Related to my earlier comment about whether the Google Picker can use an Allow file access dialog when the authorization popup window is open like the Canvas Picker does: once all the error-handling for the Canvas Picker is in place the intended behaviour of the Canvas Picker whenever something goes wrong (for example the file list proxy API responds with an error) is that it should return to this view:

  

  As a bonus it might show an error message under the To select a file, you must authorize Hypothesis to access your files in Canvas sentence (and this is where a link to our support page, and details of what went wrong, could go) but the main thing is that it:

  1. Has an Authorize button so that the user can try starting again
  2. Has a Cancel button so the user can go back and use a different type of file instead

  The current behaviour when the Google Picker fails is to show this error dialog, which is different from the Canvas Picker's behaviour and lacks 1 and 2:

  

  (The X on that dialog doesn't seem to work, but I think we should be getting rid of the dialog entirely anyway.)

[robertknight]

(The X on that dialog doesn't seem to work, but I think we should be getting rid of the dialog entirely anyway.)

That issue is now resolved on master.