Extract some logic from SuggestAppsDialog to a separate class
This extracts logic that handles loading, initializing and handling
requests from web store widget out of SuggestAppsDialog.
What's left in SuggestAppsDialog is logic for showing/hiding the dialog
modal to file manager, and handling results from the widget.
The goal is to eventually remove the newly created class out of
ui/file_manager so it can be used to show Web Store widget for purposes
not related to file manager.
BUG=439448
Review URL: https://codereview.chromium.org/
1068653002
Cr-Commit-Position: refs/heads/master@{#324064}