Add Apps.AppListSearchQueryLength UMA histogram.

ui/app_list/search_controller.cc

 // Copyright 2013 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 "ui/app_list/search_controller.h"
 
 #include <algorithm>
 #include <vector>
 
 #include "base/bind.h"
@@ skipping 64 matching lines @@
 }
 
 void SearchController::OpenResult(SearchResult* result, int event_flags) {
   // Count AppList.Search here because it is composed of search + action.
   base::RecordAction(base::UserMetricsAction("AppList_Search"));
 
   UMA_HISTOGRAM_ENUMERATION(kSearchResultOpenDisplayTypeHistogram,
                             result->display_type(),
                             SearchResult::DISPLAY_TYPE_LAST);
 
+  UMA_HISTOGRAM_COUNTS_100(kSearchQueryLength, search_box_->text().size());
+
   result->Open(event_flags);
 
   if (history_ && history_->IsReady()) {
     history_->AddLaunchEvent(base::UTF16ToUTF8(search_box_->text()),
                              result->id());
   }
 }
 
 void SearchController::InvokeResultAction(SearchResult* result,
                                           int action_index,
@@ skipping 26 matching lines @@
   KnownResults known_results;
   if (history_ && history_->IsReady()) {
     history_->GetKnownResults(base::UTF16ToUTF8(search_box_->text()))
         ->swap(known_results);
   }
 
   mixer_->MixAndPublish(is_voice_query_, known_results);
 }
 
 }  // namespace app_list