Fix comment typo in base/strings/string_piece.h

Only fix comment typo. No behavior changes.

Change-Id: Ie77c6614676be140551e0661474167c87b2d2646
Reviewed-on: https://chromium-review.googlesource.com/c/1292654Reviewed-by: danakj <danakj@chromium.org>
Commit-Queue: danakj <danakj@chromium.org>
Cr-Commit-Position: refs/heads/master@{#602031}

AUTHORS

@@ -467,6 +467,7 @@ Kaustubh Atrawalkar <kaustubh.a@samsung.com>
 Kaustubh Atrawalkar <kaustubh.ra@gmail.com>
 Ke He <ke.he@intel.com>
 Keene Pan <keenepan@linpus.com>
+Keita Yoshimoto <y073k3@gmail.com>
 Keith Chen <keitchen@amazon.com>
 Kenneth Rohde Christiansen <kenneth.r.christiansen@intel.com>
 Kenneth Strickland <ken.strickland@gmail.com>

base/strings/string_piece.h

@@ -386,7 +386,7 @@ extern template class BASE_EXPORT BasicStringPiece<std::string>;
 extern template class BASE_EXPORT BasicStringPiece<string16>;
 #endif
 
-// StingPiece operators --------------------------------------------------------
+// StringPiece operators -------------------------------------------------------
 
 BASE_EXPORT bool operator==(const StringPiece& x, const StringPiece& y);