Respond to CR.

Signal/src/util/DateUtil.h

@@ -29,6 +29,8 @@ NS_ASSUME_NONNULL_BEGIN
 + (NSString *)formatMessageTimestamp:(uint64_t)timestamp;
 
 + (BOOL)isTimestampFromLastHour:(uint64_t)timestamp;
+// These two "exemplary" values can be used by views to measure
+// the likely size for recent values formatted using isTimestampFromLastHour:.
 + (NSString *)exemplaryNowTimeFormat;
 + (NSString *)exemplaryMinutesTimeFormat;
 

Signal/src/util/DateUtil.m

@@ -263,6 +263,7 @@ static NSString *const DATE_FORMAT_WEEKDAY = @"EEEE";
 
     NSCalendar *calendar = [NSCalendar currentCalendar];
 
+    // Note: we are careful to treat "future" dates as "now".
     NSInteger yearsDiff = [self yearsFromFirstDate:date toSecondDate:nowDate];
     NSInteger daysDiff = [self daysFromFirstDate:date toSecondDate:nowDate];
     NSInteger minutesDiff

SignalServiceKit/src/Messages/Attachments/TSAttachmentStream.m

@@ -469,7 +469,7 @@ NS_ASSUME_NONNULL_BEGIN
     }
 
     if (result == nil) {
-        DDLogError(@"%@ Unable to build thumbnail for attachmentId: %@", self.logTag, self.uniqueId);
+        OWSFail(@"%@ Unable to build thumbnail for attachmentId: %@", self.logTag, self.uniqueId);
         return;
     }