[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();
+
+// A token is a sequences of contiguous characters separated by any of the
+// characters that are part of delimiter set {' ', '.', ',', '-', '_', '@'}.
+
+// Returns true if the |field_contents| is a substring of the |suggestion|
+// starting at token boundaries. |field_contents| can span multiple |suggestion|
+// tokens.
+bool FieldIsSuggestionSubstringStartingOnTokenBoundary(
+    const base::string16& suggestion,
+    const base::string16& field_contents,
+    bool case_sensitive);
+
+// Finds the first occurrence of a searched substring |field_contents| within
+// the string |suggestion| starting at token boundaries and returns the index to
+// the end of the located substring, or base::string16::npos if the substring is
+// not found. "preview-on-hover" feature is one such use case where the
+// substring |field_contents| may not be found within the string |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_