Update the policy documentation for sync and local sync.

components/policy/resources/policy_templates.json

Index: components/policy/resources/policy_templates.json
diff --git a/components/policy/resources/policy_templates.json b/components/policy/resources/policy_templates.json
index 0a929606809987759bf7bd45df6e9b5ec76c4872..a3d6680b3f03bde255f0942aa8f054eaab44d357 100644
--- a/components/policy/resources/policy_templates.json
+++ b/components/policy/resources/policy_templates.json
@@ -1534,7 +1534,9 @@
 
       If this policy is left not set Google Sync will be available for the user to choose whether to use it or not.
 
-      To fully disable Google Sync, it is recommended that you disable the Google Sync service in the Google Admin console.''',
+      To fully disable Google Sync, it is recommended that you disable the Google Sync service in the Google Admin console.
+
+      This policy should not be enabled when <ph name="ROAMING_PROFILE_SUPPORT_ENABLED_POLICY_NAME">RoamingProfileSupportEnabled</ph> policy is set to enabled as that feature shares the same client side functionality. The Google-hosted synchronization is disabled in this case completely.''',
       'arc_support': 'Disabling Google Sync will cause Android Backup and Restore to not function properly.',
     },
     {
@@ -1552,11 +1554,9 @@
       'tags': ['local-data-access'],
       'desc': '''If you enable this setting, the settings stored in <ph name="PRODUCT_NAME">$1<ex>Google Chrome</ex></ph> profiles like bookmarks, autofill data, passwords, etc. will also be written to a file stored in the Roaming user profile folder or a location specified by the Administrator through the <ph name="ROAMING_PROFILE_LOCATION_POLICY_NAME">$1<ex>RoamingProfileLocation</ex></ph> policy.
 
-      Google Sync is automatically disabled when this policy is enabled.
-
-      To prevent accidental data leaks it is advisable to also set the <ph name="SIGNIN_ALLOWED_POLICY_NAME">$1<ex>SigninAllowed</ex></ph> policy to False.
+      If this policy is disabled or left not set only the regular local profiles will be used.
 
-      If this policy is disabled or left not set only the regular local profiles will be used.''',
+      When roaming profiles support is used the <ph name="SYNC_DISABLED_POLICY_NAME">SyncDisabled</ph> policy should not be enabled because the support for roaming profiles relies on the same client side functionality. The Google-hosted synchronization is disabled in this case completely.''',

[Andrew T Wilson (Slow), 2017/06/14 15:05:44]

I guess I find "Google-hosted synchronization" confusing, since roaming profile
support doesn't feel like "Google-hosted synchronization".

Maybe up above it should say something like "SyncDisabled disables all data
synchronization, overriding RoamingProfileSupportEnabled"?

Somewhere in this documentation it should be made clear that setting
RomaingProfileSupportEnabled=true will disable cloud sync.

[pastarmovj, 2017/07/03 11:14:58]

Finally came around to addressing this. I like the suggestion it makes it
cleaner and down to the point. :)

       'label': '''Enable the creation of roaming copies for <ph name="PRODUCT_NAME">$1<ex>Google Chrome</ex></ph> profile data.''',
     },
     {