Teach PasswordAutofillAgent sometimes match prefixes of usernames

components/autofill/core/common/autofill_util.cc

 // 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.
 
 #include "components/autofill/core/common/autofill_util.h"
 
 #include <algorithm>
 
 #include "base/command_line.h"
 #include "base/feature_list.h"
@@ skipping 16 matching lines @@
     "animation_duration_millis";
 const char kAutofillKeyboardAccessoryLimitLabelWidthKey[] =
     "should_limit_label_width";
 const char kAutofillKeyboardAccessoryHintKey[] =
     "is_hint_shown_before_suggestion";
 
 namespace {
 
 const char kSplitCharacters[] = " .,-_@";
 
+const char kPrefixMatchTockens[] = "@";
+
 template <typename Char>
 struct Compare : base::CaseInsensitiveCompareASCII<Char> {
   explicit Compare(bool case_sensitive) : case_sensitive_(case_sensitive) {}
   bool operator()(Char x, Char y) const {
     return case_sensitive_ ? (x == y)
                            : base::CaseInsensitiveCompareASCII<Char>::
                              operator()(x, y);
   }
 
  private:
@@ skipping 45 matching lines @@
 bool IsHintEnabledInKeyboardAccessory() {
 #if defined(OS_ANDROID)
   return base::GetFieldTrialParamByFeatureAsBool(
       kAutofillKeyboardAccessory, kAutofillKeyboardAccessoryHintKey, false);
 #else  // !defined(OS_ANDROID)
   NOTREACHED();
   return false;
 #endif
 }
 
-bool FieldIsSuggestionSubstringStartingOnTokenBoundary(
-    const base::string16& suggestion,
-    const base::string16& field_contents,
-    bool case_sensitive) {
+bool IsSubstringStartingOnTokenBoundary(const base::string16& suggestion,
+                                        const base::string16& field_contents,
+                                        bool case_sensitive) {
   if (!IsFeatureSubstringMatchEnabled()) {
     return base::StartsWith(suggestion, field_contents,
                             case_sensitive
                                 ? base::CompareCase::SENSITIVE
                                 : base::CompareCase::INSENSITIVE_ASCII);
   }
 
   return suggestion.length() >= field_contents.length() &&
          GetTextSelectionStart(suggestion, field_contents, case_sensitive) !=
              base::string16::npos;
 }
 
+bool IsPrefixStartingOnTokenBoundary(const base::string16& full_string,
+                                     const base::string16& prefix,
+                                     bool case_sensitive) {
+  if (base::StartsWith(full_string, prefix,
+                       case_sensitive ? base::CompareCase::SENSITIVE
+                                      : base::CompareCase::INSENSITIVE_ASCII)) {
+    if (full_string.size() > prefix.size()) {
+      char token = full_string[prefix.size()];
+
+      const std::string tokens(kPrefixMatchTockens);

[dvadym, 2017/06/01 12:15:56]

Since kPrefixMatchTockens is array only with 1 element, my feeling that it's
better to keep things simple and just make const char not const char[], that
would allow avoid creating a string here. Or you can even avoid creating a
constant by directly checking full_string[prefix.size()] == '@'.

If we ever decide to expand on another tokens, const array could be easily
added.

+      return tokens.find(token) != std::string::npos;
+    }
+  }
+  return false;
+}
+
 size_t GetTextSelectionStart(const base::string16& suggestion,
                              const base::string16& field_contents,
                              bool case_sensitive) {
   const base::string16 kSplitChars = base::ASCIIToUTF16(kSplitCharacters);
 
   // Loop until we find either the |field_contents| is a prefix of |suggestion|
   // or character right before the match is one of the splitting characters.
   for (base::string16::const_iterator it = suggestion.begin();
        (it = std::search(
             it, suggestion.end(), field_contents.begin(), field_contents.end(),
@@ skipping 48 matching lines @@
 }
 
 std::vector<std::string> LowercaseAndTokenizeAttributeString(
     const std::string& attribute) {
   return base::SplitString(base::ToLowerASCII(attribute),
                            base::kWhitespaceASCII, base::TRIM_WHITESPACE,
                            base::SPLIT_WANT_NONEMPTY);
 }
 
 }  // namespace autofill