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

components/autofill/content/renderer/password_autofill_agent.cc

Index: components/autofill/content/renderer/password_autofill_agent.cc
diff --git a/components/autofill/content/renderer/password_autofill_agent.cc b/components/autofill/content/renderer/password_autofill_agent.cc
index 9999d26e2c38dbc120a14996b5593fa49264096f..4cc20d87bf7ae1f08e16dfa5dcdc88a2152c7231 100644
--- a/components/autofill/content/renderer/password_autofill_agent.cc
+++ b/components/autofill/content/renderer/password_autofill_agent.cc
@@ -18,6 +18,7 @@
 #include "components/autofill/content/renderer/renderer_save_password_progress_logger.h"
 #include "components/autofill/core/common/autofill_constants.h"
 #include "components/autofill/core/common/autofill_switches.h"
+#include "components/autofill/core/common/autofill_util.h"
 #include "components/autofill/core/common/form_field_data.h"
 #include "components/autofill/core/common/password_form.h"
 #include "components/autofill/core/common/password_form_fill_data.h"
@@ -226,7 +227,8 @@ bool DoUsernamesMatch(const base::string16& username1,
                       bool exact_match) {
   if (exact_match)
     return username1 == username2;
-  return base::StartsWith(username1, username2, base::CompareCase::SENSITIVE);
+  return base::StartsWith(username1, username2, base::CompareCase::SENSITIVE) ||

[vabr (Chromium), 2015/07/09 06:17:51]

I understand that the StartsWith call is there in case when
IsFeatureSubstringMatchEnabled returns false (because otherwise the test is
duplicated in ContainsTokenThatStartsWith). I'm not happy about the duplication,
and about the need to think about removing it once substring matching becomes
100% launched. So I suggest to change ContainsTokenThatStartsWith to try
matching from the begin every time, and from other token boundaries depending on
IsFeatureSubstringMatchEnabled. Then you can delete StartsWith here completely.

[Pritam Nikam, 2015/07/10 16:58:45]

For autofill & CC suggestions we are using base::StartsWith(...) and
ContainsTokenThatStartsWith(...) to identify suggestions with PREFIX or
SUBSTRING matched so that we can order them. IMO, if we move
base::StartsWith(...) to ContainsTokenThatStartsWith(...) it would be difficult
to do so by just making a single call to ContainsTokenThatStartsWith(...). To
keep the API usage consistent across, let this be as it is.

[vabr (Chromium), 2015/07/13 14:04:25]

I don't understand what you mean.
FieldIsSuggestionSubstringStartingOnTokenBoundary already does prefix matching,
as a particular case of the substring matching. You can still call StartsWith
elsewhere first to check if there is a prefix match, as you do now. Here there
is no need to distinguish prefix and non-prefix matches (no ranking based on
it), so there is no need to call StartsWith. Except for
FieldIsSuggestionSubstringStartingOnTokenBoundary no doing any matching when
substring is not allowed. I don't see how this is about consistency in API
usage. Consistent API usage does not mean that everybody using the API will
compute the same thing. I don't agree with letting this be as it is for the
"consistency" argument.

[Pritam Nikam, 2015/07/14 10:30:07]

Done.

+         ContainsTokenThatStartsWith(username1, username2, true);
 }
 
 // Returns |true| if the given element is editable. Otherwise, returns |false|.
@@ -421,11 +423,8 @@ bool FillUserNameAndPassword(
     username_element->setValue(username, true);

[vabr (Chromium), 2015/07/09 08:27:50]

Please add:
// TODO(vabr): Why not setSuggestedValue? http://crbug.com/507714

[Pritam Nikam, 2015/07/10 16:58:46]

Done.

     nonscript_modified_values[*username_element] = username;
     username_element->setAutofilled(true);
-
-    if (set_selection) {
-      username_element->setSelectionRange(current_username.length(),
-                                          username.length());
-    }
+    if (set_selection)
+      PreviewSuggestion(username, current_username, username_element);
   } else if (current_username != username) {
     // If the username can't be filled and it doesn't match a saved password
     // as is, don't autofill a password.
@@ -572,7 +571,6 @@ PasswordAutofillAgent::PasswordAutofillAgent(content::RenderFrame* render_frame)
       logging_state_active_(false),
       was_username_autofilled_(false),
       was_password_autofilled_(false),
-      username_selection_start_(0),
       did_stop_loading_(false),
       weak_ptr_factory_(this) {
   Send(new AutofillHostMsg_PasswordAutofillAgentConstructed(routing_id()));
@@ -799,14 +797,14 @@ bool PasswordAutofillAgent::PreviewSuggestion(
     return false;
   }
 
+  if (username_query_prefix_.empty())
+    username_query_prefix_ = username_element.value();
+
   was_username_autofilled_ = username_element.isAutofilled();
-  username_selection_start_ = username_element.selectionStart();
   username_element.setSuggestedValue(username);
   username_element.setAutofilled(true);
-  username_element.setSelectionRange(
-      username_selection_start_,
-      username_element.suggestedValue().length());
-
+  ::autofill::PreviewSuggestion(username_element.suggestedValue(),
+                                username_query_prefix_, &username_element);
   was_password_autofilled_ = password_info->password_field.isAutofilled();
   password_info->password_field.setSuggestedValue(password);
   password_info->password_field.setAutofilled(true);
@@ -1369,6 +1367,7 @@ bool PasswordAutofillAgent::ShowSuggestionPopup(
       routing_id(), key_it->second, field.text_direction, username_string,
       options, bounding_box_scaled));
 
+  username_query_prefix_ = username_string;
   bool suggestions_present = false;
   if (GetSuggestionsStats(fill_data, username_string, show_all,
                           &suggestions_present)) {
@@ -1446,7 +1445,7 @@ void PasswordAutofillAgent::ClearPreview(
   if (!username->suggestedValue().isEmpty()) {
     username->setSuggestedValue(blink::WebString());
     username->setAutofilled(was_username_autofilled_);
-    username->setSelectionRange(username_selection_start_,
+    username->setSelectionRange(username_query_prefix_.length(),
                                 username->value().length());
   }
   if (!password->suggestedValue().isEmpty()) {