Removes code that was used for Chrome macOS 10.10-

On macOS versions running versions below 10.10 images did not conform to
NSSecureCoding protocol. Now that Chrome only supports macOS 10.10+ this
check is unnecessary.

Bug: None
Change-Id: Ief414b6e6e7f183b2e9e2b5065231579b92578e0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2494873Reviewed-by: Robert Sesek <rsesek@chromium.org>
Commit-Queue: Mohamed Adel <adelm@google.com>
Cr-Commit-Position: refs/heads/master@{#820321}

chrome/browser/ui/cocoa/notifications/notification_builder_mac.mm

@@ -17,13 +17,8 @@
   if (!icon)
     return;
 
-  if ([icon conformsToProtocol:@protocol(NSSecureCoding)]) {
-    [_notificationData setObject:icon
-                          forKey:notification_constants::kNotificationIcon];
-  } else {  // NSImage only conforms to NSSecureCoding from 10.10 onwards.
-    [_notificationData setObject:[icon TIFFRepresentation]
-                          forKey:notification_constants::kNotificationIcon];
-  }
+  [_notificationData setObject:icon
+                        forKey:notification_constants::kNotificationIcon];
 }
 
 - (NSUserNotification*)buildUserNotification {
@@ -41,16 +36,9 @@
   // Icon
   if ([_notificationData
           objectForKey:notification_constants::kNotificationIcon]) {
-    if ([[NSImage class] conformsToProtocol:@protocol(NSSecureCoding)]) {
-      NSImage* image = [_notificationData
-          objectForKey:notification_constants::kNotificationIcon];
-      [toast setContentImage:image];
-    } else {  // NSImage only conforms to NSSecureCoding from 10.10 onwards.
-      base::scoped_nsobject<NSImage> image([[NSImage alloc]
-          initWithData:[_notificationData objectForKey:notification_constants::
-                                                           kNotificationIcon]]);
-      [toast setContentImage:image];
-    }
+    NSImage* image = [_notificationData
+        objectForKey:notification_constants::kNotificationIcon];
+    [toast setContentImage:image];
   }
 
   // Type (needed to define the buttons)