Several changes to speed up the ShortcutsProvider:

chrome/browser/autocomplete/shortcuts_provider.h

Index: chrome/browser/autocomplete/shortcuts_provider.h
===================================================================
--- chrome/browser/autocomplete/shortcuts_provider.h	(revision 148288)
+++ chrome/browser/autocomplete/shortcuts_provider.h	(working copy)
@@ -5,6 +5,7 @@
 #ifndef CHROME_BROWSER_AUTOCOMPLETE_SHORTCUTS_PROVIDER_H_
 #define CHROME_BROWSER_AUTOCOMPLETE_SHORTCUTS_PROVIDER_H_
 
+#include <map>
 #include <set>
 #include <string>
 
@@ -32,11 +33,13 @@
   virtual void DeleteMatch(const AutocompleteMatch& match) OVERRIDE;
 
  private:
+  friend class ClassifyTest;
   friend class ShortcutsProviderTest;
-  FRIEND_TEST_ALL_PREFIXES(ShortcutsProviderTest, ClassifyAllMatchesInString);
   FRIEND_TEST_ALL_PREFIXES(ShortcutsProviderTest, CalculateScore);
   FRIEND_TEST_ALL_PREFIXES(ShortcutsProviderTest, DeleteMatch);
 
+  typedef std::multimap<char16, string16> WordMap;
+
   virtual ~ShortcutsProvider();
 
   // ShortcutsBackendObserver:
@@ -49,23 +52,39 @@
   void GetMatches(const AutocompleteInput& input);
 
   AutocompleteMatch ShortcutToACMatch(
-      const AutocompleteInput& input,
+      int relevance,
       const string16& terms,
       const history::ShortcutsBackend::Shortcut& shortcut);
 
+  // Returns a map mapping characters to groups of words from |text| that start
+  // with those characters, ordered lexicographically descending so that longer
+  // words appear before their prefixes (if any) within a particular
+  // equal_range().
+  static WordMap CreateWordMapForString(const string16& text);
+
   // Given |text| and a corresponding base set of classifications
   // |original_class|, adds ACMatchClassification::MATCH markers for all
-  // instances of the words from |find_text| within |text| and returns the
-  // resulting classifications.
+  // instances of the words from |find_words| within |text| and returns the
+  // resulting classifications.  (|find_text| is provided as the original string
+  // used to create |find_words|.  This is supplied because it's common for this
+  // to be a prefix of |text|, so we can quickly check for that and mark that
+  // entire substring as a match before proceeding with the more generic
+  // algorithm.)
   //
   // For example, given the |text|
   // "Sports and News at sports.somesite.com - visit us!" and |original_class|
   // {{0, NONE}, {18, URL}, {37, NONE}} (marking "sports.somesite.com" as a
   // URL), calling with |find_text| set to "sp ew" would return
   // {{0, MATCH}, {2, NONE}, {12, MATCH}, {14, NONE}, {18, URL|MATCH},
-  // {20, URL}, {37, NONE}}
+  // {20, URL}, {37, NONE}}.
+  //
+  // |find_words| should be as constructed by CreateWordMapForString(find_text).
+  //
+  // |find_text| (and thus |find_words|) are expected to be lowercase.  |text|
+  // will be lowercased in this function.
   static ACMatchClassifications ClassifyAllMatchesInString(
       const string16& find_text,
+      const WordMap& find_words,
       const string16& text,
       const ACMatchClassifications& original_class);