[Autofill/Autocomplete Feature] Substring matching instead of prefix matching.

components/autofill/core/common/autofill_util.h

Index: components/autofill/core/common/autofill_util.h
diff --git a/components/autofill/core/common/autofill_util.h b/components/autofill/core/common/autofill_util.h
new file mode 100644
index 0000000000000000000000000000000000000000..b826591266e78590089ff91a8f2e94679521dfee
--- /dev/null
+++ b/components/autofill/core/common/autofill_util.h
@@ -0,0 +1,31 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef COMPONENTS_AUTOFILL_CORE_COMMON_AUTOFILL_UTIL_H_
+#define COMPONENTS_AUTOFILL_CORE_COMMON_AUTOFILL_UTIL_H_
+
+#include "base/strings/string16.h"
+
+namespace autofill {
+
+// Returns |true| when command line switch
+// |kEnableSuggestionsWithSubstringMatch| is on; otherwise |false|.
+bool IsFeatureSubstringMatchEnabled();
+
+// Splits field |suggestion| into tokens, separated by characters from " .,-_@".
+// Returns true if command line switch |kEnableSuggestionsWithSubstringMatch| is
+// on and |field_contents| is a prefix of some token; otherwise false.
+bool IsContentsPrefixOfSuggestionToken(const base::string16& suggestion,
+                                       const base::string16& field_contents,
+                                       bool case_sensitive);
+
+// Finds if the |field_contents| prefixes any of the |suggestion| token,
+// separated by characters from " .,-_@". Returns the start position of the text
+// selection in the field; base::string16::npos otherwise.
+size_t GetTextSelectionStart(const base::string16& suggestion,
+                             const base::string16& field_contents);
+
+}  // namespace autofill
+
+#endif  // COMPONENTS_AUTOFILL_CORE_COMMON_AUTOFILL_UTIL_H_