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

components/autofill/core/common/autofill_util.h

+// 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.
+bool IsFeatureSubstringMatchEnabled();
+
+// Returns true if the |field_contents| prefixes any of the |suggestion| tokens
+// separated by characters " .,-_@".
+bool ContainsTokenThatStartsWith(const base::string16& suggestion,
+                                 const base::string16& field_contents,
+                                 bool case_sensitive);
+
+// Finds if the |field_contents| prefixes any of the |suggestion| tokens,
+// separated by characters " .,-_@". Returns the start position of the text
+// selection in the field; base::string16::npos otherwise. "preview-on-hover"
+// feature is one such use case where |field_contents| may not match
+// |suggestion|.
+size_t GetTextSelectionStart(const base::string16& suggestion,
+                             const base::string16& field_contents,
+                             bool case_sensitive);
+
+}  // namespace autofill
+
+#endif  // COMPONENTS_AUTOFILL_CORE_COMMON_AUTOFILL_UTIL_H_