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

components/autofill/content/renderer/password_autofill_agent.cc

 // Copyright 2013 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/content/renderer/password_autofill_agent.h"
 
+#include <algorithm>
+
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop/message_loop.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/strings/utf_string_conversions.h"
 #include "components/autofill/content/common/autofill_messages.h"
 #include "components/autofill/content/renderer/form_autofill_util.h"
 #include "components/autofill/content/renderer/password_form_conversion_utils.h"
@@ skipping 754 matching lines @@
 
   password_info->password_field.setValue(password, true);
   password_info->password_field.setAutofilled(true);
 
   filled_element.setSelectionRange(filled_element.value().length(),
                                    filled_element.value().length());
 
   return true;
 }
 
-bool PasswordAutofillAgent::PreviewSuggestion(
-    const blink::WebNode& node,
-    const blink::WebString& username,
-    const blink::WebString& password) {
+bool PasswordAutofillAgent::PreviewSuggestion(const blink::WebNode& node,
+                                              const blink::WebString& username,
+                                              const blink::WebString& password,
+                                              int match_start) {
   blink::WebInputElement username_element;
   PasswordInfo* password_info;
 
   if (!FindLoginInfo(node, &username_element, &password_info) ||
       !IsElementAutocompletable(username_element) ||
       !IsElementAutocompletable(password_info->password_field)) {
     return false;
   }
 
   was_username_autofilled_ = username_element.isAutofilled();
-  username_selection_start_ = username_element.selectionStart();
+  username_selection_start_ =
+      std::min(match_start, username_element.maxLength());
   username_element.setSuggestedValue(username);
   username_element.setAutofilled(true);
   username_element.setSelectionRange(
       username_selection_start_,
       username_element.suggestedValue().length());
 
   was_password_autofilled_ = password_info->password_field.isAutofilled();
   password_info->password_field.setSuggestedValue(password);
   password_info->password_field.setAutofilled(true);
 
@@ skipping 684 matching lines @@
 void PasswordAutofillAgent::LegacyPasswordAutofillAgent::DidStopLoading() {
   agent_->DidStopLoading();
 }
 
 void PasswordAutofillAgent::LegacyPasswordAutofillAgent::
     DidStartProvisionalLoad(blink::WebLocalFrame* navigated_frame) {
   agent_->LegacyDidStartProvisionalLoad(navigated_frame);
 }
 
 }  // namespace autofill