Migrate SequencedTaskRunnerHandle calls to TaskRunnerHandle calls.

components/safe_json/safe_json_parser.h

Index: components/safe_json/safe_json_parser.h
diff --git a/components/safe_json/safe_json_parser.h b/components/safe_json/safe_json_parser.h
index 6b66ba431b6a7a9f283e21534152cdef43439e9c..0958f1b7f96fdee395b149be99e46bb8d524b347 100644
--- a/components/safe_json/safe_json_parser.h
+++ b/components/safe_json/safe_json_parser.h
@@ -19,8 +19,8 @@ namespace safe_json {
 // SafeJsonParser parses a given JSON safely via a platform-dependent mechanism
 // (like parsing it in a utility process or in a memory-safe environment).
 // Internally, an instance of this class is created when Parse() is called and
-// is kept alive until one of the two callbacks is called, after which it
-// deletes itself.
+// is kept alive until one of the two callbacks is executed on the original
+// caller's TaskRunner, after which it deletes itself.
 class SafeJsonParser {
  public:
   using SuccessCallback = base::Callback<void(std::unique_ptr<base::Value>)>;