[MDCSwitch] Created some missing getters for properties.

Reviewers: iangordon, #material_components_ios_owners, ajsecord

Reviewed By: #material_components_ios_owners, ajsecord

Projects: #material_components_ios_owners

Differential Revision: http://codereview.cc/D83

Author: randallli

components/Switch/src/MDCSwitch.m

@@ -99,34 +99,54 @@ - (void)layoutSubviews {
   // TODO(iangordon): Handle BiDi layouts
 }
 
+- (UIColor *)onTintColor {
+  return _thumbTrack.primaryColor;
+}
+
 - (void)setOnTintColor:(UIColor *)onTintColor {
   if (onTintColor == nil) {
     onTintColor = [[self class] defaultOnTintColor];
   }
   _thumbTrack.primaryColor = onTintColor;
 }
 
+- (UIColor *)offThumbColor {
+  return _thumbTrack.thumbOffColor;
+}
+
 - (void)setOffThumbColor:(UIColor *)offThumbColor {
   if (offThumbColor == nil) {
     offThumbColor = [[self class] defaultOffThumbColor];
   }
   _thumbTrack.thumbOffColor = offThumbColor;
 }
 
+- (UIColor *)disabledThumbColor {
+  return _thumbTrack.thumbDisabledColor;
+}
+
 - (void)setDisabledThumbColor:(UIColor *)disabledThumbColor {
   if (disabledThumbColor == nil) {
     disabledThumbColor = [MDCSwitch defaultDisabledThumbColor];
   }
   _thumbTrack.thumbDisabledColor = disabledThumbColor;
 }
 
+- (UIColor *)offTrackColor {
+  return _thumbTrack.trackOffColor;
+}
+
 - (void)setOffTrackColor:(UIColor *)offTrackColor {
   if (offTrackColor == nil) {
     offTrackColor = [MDCSwitch defaultOffTrackColor];
   }
   _thumbTrack.trackOffColor = offTrackColor;
 }
 
+- (UIColor *)disabledTrackColor {
+  return _thumbTrack.trackDisabledColor;
+}
+
 - (void)setDisabledTrackColor:(UIColor *)disabledTrackColor {
   if (disabledTrackColor == nil) {
     disabledTrackColor = [MDCSwitch defaultDisabledTrackColor];