[3 of 4] Speedup GetRegistryLengthImpl() by seeding the DAFSA in reverse

net/base/lookup_string_in_fixed_set_unittest.cc

Index: net/base/lookup_string_in_fixed_set_unittest.cc
diff --git a/net/base/lookup_string_in_fixed_set_unittest.cc b/net/base/lookup_string_in_fixed_set_unittest.cc
index 612f6406eaaa4784bb278d996a8b63d126a98741..26b2b2c36c064f4c2fb3dc705081076469892dac 100644
--- a/net/base/lookup_string_in_fixed_set_unittest.cc
+++ b/net/base/lookup_string_in_fixed_set_unittest.cc
@@ -4,8 +4,6 @@
 
 #include "net/base/lookup_string_in_fixed_set.h"
 
-#include <string.h>
-
 #include <algorithm>
 #include <limits>
 #include <ostream>
@@ -16,6 +14,7 @@
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/path_service.h"
+#include "base/strings/string_piece.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ -50,8 +49,9 @@ void PrintTo(const Expectation& expectation, std::ostream* os) {
 class LookupStringInFixedSetTest : public testing::TestWithParam<Expectation> {
  protected:
   template <size_t N>
-  int LookupInGraph(const unsigned char(&graph)[N], const char* key) {
-    return LookupStringInFixedSet(graph, N, key, strlen(key));
+  int LookupInGraph(const unsigned char (&graph)[N], base::StringPiece key) {
+    std::string rev_key(key.rbegin(), key.rend());

[Ryan Sleevi, 2017/03/06 17:20:04]

Is it worth documenting why this is reversed?

+    return LookupStringInFixedSet(graph, N, rev_key.data(), rev_key.length());
   }
 };
 
@@ -73,7 +73,7 @@ void RecursivelyEnumerateDafsaLanguage(const FixedSetIncrementalLookup& lookup,
                                        std::vector<std::string>* language) {
   int result = lookup.GetResultForCurrentSequence();
   if (result != kDafsaNotFound) {
-    std::string line(sequence->begin(), sequence->end());
+    std::string line(sequence->rbegin(), sequence->rend());

[Ryan Sleevi, 2017/03/06 17:20:04]

Similarly

     line += base::StringPrintf(", %d", result);
     language->emplace_back(std::move(line));
   }