Respond to CR.

SignalMessaging/categories/UIColor+OWS.h

@@ -51,7 +51,6 @@ NS_ASSUME_NONNULL_BEGIN
 @property (class, readonly, nonatomic) UIColor *ows_whiteColor;
 @property (class, readonly, nonatomic) UIColor *ows_gray02Color;
 @property (class, readonly, nonatomic) UIColor *ows_gray05Color;
-@property (class, readonly, nonatomic) UIColor *ows_gray15Color;
 @property (class, readonly, nonatomic) UIColor *ows_gray25Color;
 @property (class, readonly, nonatomic) UIColor *ows_gray45Color;
 @property (class, readonly, nonatomic) UIColor *ows_gray60Color;

SignalMessaging/categories/UIColor+OWS.m

@@ -159,11 +159,6 @@ NS_ASSUME_NONNULL_BEGIN
     return [UIColor colorWithRGBHex:0xEEEFEF];
 }
 
-+ (UIColor *)ows_gray15Color
-{
-    return [UIColor colorWithRGBHex:0xD5D6D6];
-}
-
 + (UIColor *)ows_gray25Color
 {
     return [UIColor colorWithRGBHex:0xBBBDBE];