Adds some histograms from various omnibox queries. I'm doing this as

chrome/browser/autocomplete/history_quick_provider.cc

 // Copyright (c) 2011 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/autocomplete/history_quick_provider.h"
 
 #include "base/basictypes.h"
 #include "base/i18n/break_iterator.h"
 #include "base/logging.h"
+#include "base/metrics/histogram.h"
+#include "base/string_number_conversions.h"
 #include "base/string_util.h"
+#include "base/time.h"
 #include "base/utf_string_conversions.h"
 #include "chrome/browser/history/history.h"
 #include "chrome/browser/history/in_memory_url_index.h"
 #include "chrome/browser/net/url_fixer_upper.h"
 #include "chrome/browser/prefs/pref_service.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/common/pref_names.h"
 #include "chrome/common/url_constants.h"
 #include "googleurl/src/url_parse.h"
 #include "content/common/notification_source.h"
@@ skipping 34 matching lines @@
     // have cases where this happens offhand).  We can't do anything with
     // empty input, so just bail; otherwise we'd crash later.
     return;
   }
   autocomplete_input_.set_text(fixed_text);
 
   // TODO(pkasting): We should just block here until this loads.  Any time
   // someone unloads the history backend, we'll get inconsistent inline
   // autocomplete behavior here.
   if (GetIndex()) {
+    base::TimeTicks start_time = base::TimeTicks::Now();
     DoAutocomplete();
+    if (input.text().size() < 6) {
+      base::TimeTicks end_time = base::TimeTicks::Now();
+      std::string name = "HistoryQuickProvider.QueryIndexTime." +
+          base::IntToString(input.text().size());
+      scoped_refptr<base::Histogram> counter = base::Histogram::FactoryGet(
+          name, 1, 1000, 50, base::Histogram::kUmaTargetedHistogramFlag);
+      counter->Add(static_cast<int>((end_time - start_time).InMilliseconds()));
+    }
     UpdateStarredStateOfMatches();
   }
 }
 
 // HistoryQuickProvider matches are currently not deletable.
 // TODO(mrossetti): Determine when a match should be deletable.
 void HistoryQuickProvider::DeleteMatch(const AutocompleteMatch& match) {}
 
 void HistoryQuickProvider::DoAutocomplete() {
   // Get the matching URLs from the DB.
@@ skipping 117 matching lines @@
       ++i;
     } while ((i < match_count) && (offset == matches[i].offset - adjust));
     if (offset < text_length) {
       spans.push_back(ACMatchClassification(offset,
                                             ACMatchClassification::NONE));
     }
   }
 
   return spans;
 }