Remove trailing whitespace.

Also adds a presubmit to prevent adding trailing whitespace to source
code in the future.

Change-Id: I41a4df81487f6f00aa19b188f0cac6a3377efde6
Reviewed-on: https://skia-review.googlesource.com/57380
Reviewed-by: Ravi Mistry <rmistry@google.com>
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>
diff --git a/include/private/GrAuditTrail.h b/include/private/GrAuditTrail.h
index 05f6fc5..c617550 100644
--- a/include/private/GrAuditTrail.h
+++ b/include/private/GrAuditTrail.h
@@ -23,13 +23,13 @@
  * to json.
  *
  * Capturing this information is expensive and consumes a lot of memory, therefore it is important
- * to enable auditing only when required and disable it promptly. The AutoEnable class helps to 
+ * to enable auditing only when required and disable it promptly. The AutoEnable class helps to
  * ensure that the audit trail is disabled in a timely fashion. Once the information has been dealt
  * with, be sure to call reset(), or the log will simply keep growing.
  */
 class GrAuditTrail {
 public:
-    GrAuditTrail() 
+    GrAuditTrail()
     : fClientID(kGrAuditTrailInvalidID)
     , fEnabled(false) {}