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

components/autofill/core/browser/autocomplete_history_manager.cc

Index: components/autofill/core/browser/autocomplete_history_manager.cc
diff --git a/components/autofill/core/browser/autocomplete_history_manager.cc b/components/autofill/core/browser/autocomplete_history_manager.cc
index 44e766660ead2209857df440c279c8a45a6b0a3a..a5bddb54b1e9c112596954f998a805cdec9eb21b 100644
--- a/components/autofill/core/browser/autocomplete_history_manager.cc
+++ b/components/autofill/core/browser/autocomplete_history_manager.cc
@@ -9,6 +9,7 @@
 #include "base/prefs/pref_service.h"
 #include "base/profiler/scoped_tracker.h"
 #include "base/strings/string16.h"
+#include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "components/autofill/core/browser/autofill_client.h"
 #include "components/autofill/core/browser/autofill_driver.h"
@@ -16,6 +17,7 @@
 #include "components/autofill/core/browser/autofill_external_delegate.h"
 #include "components/autofill/core/browser/validation.h"
 #include "components/autofill/core/common/autofill_pref_names.h"
+#include "components/autofill/core/common/autofill_util.h"
 #include "components/autofill/core/common/form_data.h"
 
 namespace autofill {
@@ -82,7 +84,30 @@ void AutocompleteHistoryManager::OnWebDataServiceRequestDone(
   const WDResult<std::vector<base::string16> >* autofill_result =
       static_cast<const WDResult<std::vector<base::string16> >*>(result);
   std::vector<base::string16> suggestions = autofill_result->GetValue();
-  SendSuggestions(&suggestions);
+
+  if (!IsFeatureSubstringMatchEnabled() || pending_query_prefix_.empty()) {
+    SendSuggestions(&suggestions);
+  } else {
+    std::vector<base::string16> preferred_suggestions;
+    std::vector<base::string16> substring_matched_suggestions;
+    for (base::string16 suggestion : suggestions) {

[please use gerrit instead, 2015/06/29 22:06:28]

const base::string16&

[Pritam Nikam, 2015/06/30 15:05:50]

Done.

+      if (StartsWith(suggestion, pending_query_prefix_, false)) {
+        preferred_suggestions.push_back(suggestion);
+      } else if (ContainsTokenThatStartsWith(suggestion, pending_query_prefix_,
+                                             false)) {
+        substring_matched_suggestions.push_back(suggestion);
+      }
+    }
+
+    // Prefix matches should precede other token matches.
+    if (IsFeatureSubstringMatchEnabled()) {
+      preferred_suggestions.insert(preferred_suggestions.end(),
+                                   substring_matched_suggestions.begin(),
+                                   substring_matched_suggestions.end());
+    }
+
+    SendSuggestions(&preferred_suggestions);
+  }
 }
 
 void AutocompleteHistoryManager::OnGetAutocompleteSuggestions(
@@ -103,8 +128,14 @@ void AutocompleteHistoryManager::OnGetAutocompleteSuggestions(
   }
 
   if (database_.get()) {
+    // TODO(pritam.nikam): Prensently there is unavailability of SQL solutions
+    // to handle '_' along LIKE operator on Chromium Linux bot. Patterns like
+    // '%s\_foo%' and '%[_]foo%' are not working. Revisit below code snippet in
+    // future so that logic can be handled in SQL query instead.

[please use gerrit instead, 2015/06/29 22:06:28]

No need for "Revisit.." sentence and TODO marker. Instead, please find the
sqlite documentation that explains why sqlite filtering will not work for our
case and paste the link in the comment.

[Pritam Nikam, 2015/06/30 15:05:50]

With ESCAPE clause its working. I've modified
|AutofillTable::GetFormValuesForElementName()|.

SELECT value FROM table
  WHERE value LIKE '%!_foo%' ESCAPE '!'

+    pending_query_prefix_ = prefix;
     pending_query_handle_ = database_->GetFormValuesForElementName(
-        name, prefix, kMaxAutocompleteMenuItems, this);
+        name, IsFeatureSubstringMatchEnabled() ? base::string16() : prefix,
+        kMaxAutocompleteMenuItems, this);
   }
 }