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

components/autofill/content/renderer/form_autofill_util.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/form_autofill_util.h"
 
 #include <map>
 #include <set>
 
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/memory/scoped_vector.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "components/autofill/core/common/autofill_data_validation.h"
 #include "components/autofill/core/common/autofill_regexes.h"
 #include "components/autofill/core/common/autofill_switches.h"
+#include "components/autofill/core/common/autofill_util.h"
 #include "components/autofill/core/common/form_data.h"
 #include "components/autofill/core/common/form_field_data.h"
 #include "third_party/WebKit/public/platform/WebString.h"
 #include "third_party/WebKit/public/platform/WebVector.h"
 #include "third_party/WebKit/public/web/WebDocument.h"
 #include "third_party/WebKit/public/web/WebElement.h"
 #include "third_party/WebKit/public/web/WebElementCollection.h"
 #include "third_party/WebKit/public/web/WebFormControlElement.h"
 #include "third_party/WebKit/public/web/WebFormElement.h"
 #include "third_party/WebKit/public/web/WebInputElement.h"
@@ skipping 835 matching lines @@
       data.value.substr(0, input_element->maxLength()));
     input_element->setAutofilled(true);
   } else if (IsTextAreaElement(*field) || IsSelectElement(*field)) {
     field->setSuggestedValue(data.value);
     field->setAutofilled(true);
   }
 
   if (is_initiating_node &&
       (IsTextInput(input_element) || IsTextAreaElement(*field))) {
     // Select the part of the text that the user didn't type.
-    int start = field->value().length();
-    int end = field->suggestedValue().length();
-    field->setSelectionRange(start, end);
+    PreviewSuggestion(field->suggestedValue(), field->value(), field);
   }
 }
 
 // Recursively checks whether |node| or any of its children have a non-empty
 // bounding box. The recursion depth is bounded by |depth|.
 bool IsWebNodeVisibleImpl(const blink::WebNode& node, const int depth) {
   if (depth < 0)
     return false;
   if (node.hasNonEmptyBoundingBox())
     return true;
@@ skipping 640 matching lines @@
 }
 
 gfx::RectF GetScaledBoundingBox(float scale, WebElement* element) {
   gfx::Rect bounding_box(element->boundsInViewportSpace());
   return gfx::RectF(bounding_box.x() * scale,
                     bounding_box.y() * scale,
                     bounding_box.width() * scale,
                     bounding_box.height() * scale);
 }
 
+void PreviewSuggestion(const base::string16& suggestion,
+                       const base::string16& user_input,
+                       blink::WebFormControlElement* input_element) {
+  size_t selection_start = user_input.length();
+  if (IsFeatureSubstringMatchEnabled()) {
+    size_t offset =
+        autofill::GetTextSelectionStart(suggestion, user_input, false);
+    // Zero selection start is for password manager, which can show usernames
+    // that do not begin with the user input value.
+    selection_start = (offset == base::string16::npos) ? 0 : offset;
+  }
+
+  input_element->setSelectionRange(selection_start, suggestion.length());
+}
+
 }  // namespace autofill