Assume all providers may give zero suggest responses.

chrome/browser/autocomplete/history_url_provider.cc

 // Copyright (c) 2012 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_url_provider.h"
 
 #include <algorithm>
 
 #include "base/basictypes.h"
 #include "base/bind.h"
@@ skipping 463 matching lines @@
 HistoryURLProvider::HistoryURLProvider(AutocompleteProviderListener* listener,
                                        Profile* profile)
     : HistoryProvider(profile, AutocompleteProvider::TYPE_HISTORY_URL),
       listener_(listener),
       params_(NULL) {
   // Initialize HUP scoring params based on the current experiment.
   OmniboxFieldTrial::GetExperimentalHUPScoringParams(&scoring_params_);
 }
 
 void HistoryURLProvider::Start(const AutocompleteInput& input,
-                               bool minimal_changes) {
+                               bool minimal_changes,
+                               bool called_due_to_focus) {
   // NOTE: We could try hard to do less work in the |minimal_changes| case
   // here; some clever caching would let us reuse the raw matches from the
   // history DB without re-querying.  However, we'd still have to go back to
   // the history thread to mark these up properly, and if pass 2 is currently
   // running, we'd need to wait for it to return to the main thread before
   // doing this (we can't just write new data for it to read due to thread
   // safety issues).  At that point it's just as fast, and easier, to simply
   // re-run the query from scratch and ignore |minimal_changes|.
 
   // Cancel any in-progress query.
   Stop(false);
 
   matches_.clear();
 
-  if ((input.type() == metrics::OmniboxInputType::INVALID) ||
+  if (called_due_to_focus ||
+      (input.type() == metrics::OmniboxInputType::INVALID) ||
       (input.type() == metrics::OmniboxInputType::FORCED_QUERY))
     return;
 
   // Do some fixup on the user input before matching against it, so we provide
   // good results for local file paths, input with spaces, etc.
   const FixupReturn fixup_return(FixupUserInput(input));
   if (!fixup_return.first)
     return;
   url::Parsed parts;
   url_fixer::SegmentURL(fixup_return.second, &parts);
@@ skipping 645 matching lines @@
     AutocompleteMatch::ClassifyLocationInString(base::string16::npos, 0,
         match.contents.length(), ACMatchClassification::URL,
         &match.contents_class);
   }
   match.description = info.title();
   match.description_class =
       ClassifyDescription(params.input.text(), match.description);
   RecordAdditionalInfoFromUrlRow(info, &match);
   return match;
 }