Options/MD Settings: use new prefs to drive import data dialog

chrome/test/data/policy/policy_test_cases.json

 {
   "-- Template --": {
     "intro": "Top-level entries map a policy name to its test parameters, described below. The name of the top level entry should be of the form <policy name>[.suffix]. The optional suffix is used for defining multiple test cases for a single policy.",
 
     "os": ["List of operating systems that support this policy. Valid values:", "win", "linux", "mac", "chromeos", "android", "Defaults to empty if not specified."],
     "official_only": "Whether this policy exists in official builds only. Defaults to |false| if not specified.",
     "can_be_recommended": "Whether a recommended value may be set for the policy. Defaults to |false| if not specified.",
     "test_policy": "A policy dictionary that should make the preferences affected by this policy become policy-controlled. Usually just sets the current policy. Defaults to an empty dictionary if not specified.",
     "note": "If the policy affects any preferences, the following array should be specified with one entry per such preference.",
     "pref_mappings": [
@@ skipping 1615 matching lines @@
         ]
       }
     ]
   },
 
   "ImportBookmarks": {
     "os": ["win", "mac", "linux"],
     "can_be_recommended": true,
     "test_policy": { "ImportBookmarks": false },
     "pref_mappings": [
-      { "pref": "import_bookmarks",
+      { "pref": "import_dialog_bookmarks",
         "indicator_tests": [
           { "policy": { "ImportBookmarks": false } }
         ]
       }
     ]
   },
 
   "ImportHistory": {
     "os": ["win", "mac", "linux"],
     "can_be_recommended": true,
     "test_policy": { "ImportHistory": false },
     "pref_mappings": [
-      { "pref": "import_history",
+      { "pref": "import_dialog_history",
         "indicator_tests": [
           { "policy": { "ImportHistory": false } }
         ]
       }
     ]
   },
 
   "ImportHomepage": {
     "os": ["win", "mac", "linux"],
     "test_policy": { "ImportHomepage": false },
     "pref_mappings": [
       { "pref": "import_home_page" }
     ]
   },
 
   "ImportSearchEngine": {
     "os": ["win", "mac", "linux"],
     "can_be_recommended": true,
     "test_policy": { "ImportSearchEngine": false },
     "pref_mappings": [
-      { "pref": "import_search_engine",
+      { "pref": "import_dialog_search_engine",
         "indicator_tests": [
           { "policy": { "ImportSearchEngine": false } }
         ]
       }
     ]
   },
 
   "ImportSavedPasswords": {
     "os": ["win", "mac", "linux"],
     "can_be_recommended": true,
     "test_policy": { "ImportSavedPasswords": false },
     "pref_mappings": [
-      { "pref": "import_saved_passwords",
+      { "pref": "import_dialog_saved_passwords",
         "indicator_tests": [
           { "policy": { "ImportSavedPasswords": false } }
         ]
       }
     ]
   },
 
   "ImportAutofillFormData": {
     "os": ["win", "mac", "linux"],
     "can_be_recommended": true,
     "test_policy": { "ImportAutofillFormData": false },
     "pref_mappings": [
-      { "pref": "import_autofill_form_data",
+      { "pref": "import_dialog_autofill_form_data",
         "indicator_tests": [
           { "policy": { "ImportAutofillFormData": false } }
         ]
       }
     ]
   },
 
   "MaxConnectionsPerProxy": {
     "os": ["win", "linux", "mac", "chromeos"],
     "test_policy": { "MaxConnectionsPerProxy": 16 },
@@ skipping 1366 matching lines @@
 
   "AdditionalLaunchParameters": {
   },
 
   "SuppressChromeFrameTurndownPrompt": {
   },
 
   "SkipMetadataCheck": {
   }
 }