GH-1142 AccessBackgroundLocation only when compile & running Q (#1143)

* AccessBackgroundLocation only when compile & running Q

* put if compile check around permission

Author: jamesmontemagno

Xamarin.Essentials/Permissions/Permissions.android.cs

@@ -224,15 +224,22 @@ public override (string androidPermission, bool isRuntime)[] RequiredPermissions
 
         public partial class LocationAlways : BasePlatformPermission
         {
-            public override (string androidPermission, bool isRuntime)[] RequiredPermissions =>
-                new (string, bool)[]
+            public override (string androidPermission, bool isRuntime)[] RequiredPermissions
+            {
+                get
                 {
+                    var permissions = new List<(string, bool)>();
 #if __ANDROID_29__
-                    (Manifest.Permission.AccessBackgroundLocation, true),
+                    if (Platform.HasApiLevelQ)
+                        permissions.Add((Manifest.Permission.AccessBackgroundLocation, true));
 #endif
-                    (Manifest.Permission.AccessCoarseLocation, true),
-                    (Manifest.Permission.AccessFineLocation, true)
-                };
+
+                    permissions.Add((Manifest.Permission.AccessCoarseLocation, true));
+                    permissions.Add((Manifest.Permission.AccessFineLocation, true));
+
+                    return permissions.ToArray();
+                }
+            }
         }
 
         public partial class Maps : BasePlatformPermission

Xamarin.Essentials/Platform/Platform.android.cs

@@ -173,6 +173,13 @@ internal static AndroidUri GetShareableFileUri(string filename)
             false;
 #endif
 
+        internal static bool HasApiLevelQ =>
+#if __ANDROID_29__
+            HasApiLevel(BuildVersionCodes.Q);
+#else
+            false;
+#endif
+
         internal static bool HasApiLevel(BuildVersionCodes versionCode) =>
             (int)Build.VERSION.SdkInt >= (int)versionCode;