Add a JSON sanitizer.

components/BUILD.gn

Index: components/BUILD.gn
diff --git a/components/BUILD.gn b/components/BUILD.gn
index 539002e77e17b49b4ff1359b936022d85c5a8e94..27e21b82304e3782d6c97cee97e1622685130a91 100644
--- a/components/BUILD.gn
+++ b/components/BUILD.gn
@@ -291,6 +291,7 @@ test("components_unittests") {
     "//components/offline_pages:unit_tests",
     "//components/omnibox:unit_tests",
     "//components/packed_ct_ev_whitelist:unit_tests",
+    "//components/safe_json:unit_tests",
     "//components/undo:unit_tests",
     "//components/update_client:unit_tests",
     "//components/variations:unit_tests",
@@ -343,7 +344,10 @@ test("components_unittests") {
   }
 
   if (!is_ios) {
-    deps += [ "//components/scheduler:unit_tests" ]
+    deps += [
+      "//components/safe_json:unit_tests",
+      "//components/scheduler:unit_tests",
+    ]
   }
 }