Autocomplete entries submitted are limited in number.

chrome/browser/webdata/web_database.cc

 // Copyright (c) 2010 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 "chrome/browser/webdata/web_database.h"
 
 #include <algorithm>
 #include <limits>
 #include <set>
 #include <string>
@@ skipping 1057 matching lines @@
 }
 
 bool WebDatabase::AddFormFieldValues(const std::vector<FormField>& elements,
                                      std::vector<AutofillChange>* changes) {
   return AddFormFieldValuesTime(elements, changes, Time::Now());
 }
 
 bool WebDatabase::AddFormFieldValuesTime(const std::vector<FormField>& elements,
                                          std::vector<AutofillChange>* changes,
                                          base::Time time) {
+  // Only add one new entry for each unique element name.  Use |seen_names| to
+  // track this.  Add up to |kMaximumUniqueNames| unique entries per form.
+  const size_t kMaximumUniqueNames = 256;
+  std::set<string16> seen_names;
   bool result = true;
   for (std::vector<FormField>::const_iterator
        itr = elements.begin();
        itr != elements.end();
        itr++) {
+    if (seen_names.size() >= kMaximumUniqueNames)
+      break;
+    if (seen_names.find(itr->name()) != seen_names.end())
+      continue;
     result = result && AddFormFieldValueTime(*itr, changes, time);
+    seen_names.insert(itr->name());
   }
   return result;
 }
 
 bool WebDatabase::ClearAutofillEmptyValueElements() {
   sql::Statement s(db_.GetUniqueStatement(
       "SELECT pair_id FROM autofill WHERE TRIM(value)= \"\""));
   if (!s) {
     NOTREACHED() << "Statement prepare failed";
     return false;
@@ skipping 799 matching lines @@
 
     // Add successive versions here.  Each should set the version number and
     // compatible version number as appropriate, then fall through to the next
     // case.
 
     case kCurrentVersionNumber:
       // No migration needed.
       return;
   }
 }