Update notification style: allow 2-line titles if the message is blank.

ui/message_center/views/constants.h

Index: ui/message_center/views/constants.h
diff --git a/ui/message_center/views/constants.h b/ui/message_center/views/constants.h
index d03ec7f0b79f38c8369be8ad27c013d875ddcba9..f2995dd45b5964a0ccbc6a412727302393744095 100644
--- a/ui/message_center/views/constants.h
+++ b/ui/message_center/views/constants.h
@@ -31,8 +31,7 @@ const int kButtonTitleTopPadding = 0;
 // Character limits: Displayed text will be subject to the line limits above,
 // but we also remove trailing characters from text to reduce processing cost.
 // Character limit = pixels per line * line limit / min. pixels per character.
-const size_t kTitleCharacterLimit =
-    message_center::kNotificationWidth * message_center::kTitleLineLimit / 4;
+const int kMinPixelsPerTitleCharacter = 4;
 const size_t kMessageCharacterLimit =
     message_center::kNotificationWidth *
         message_center::kMessageExpandedLineLimit / 3;