Enable prefetch-search-results on Desktop Chrome by default.

chrome/browser/search/search.cc

 // Copyright 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/search/search.h"
 
 #include "base/command_line.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram.h"
 #include "base/prefs/pref_service.h"
@@ skipping 47 matching lines @@
 const uint64 kEmbeddedPageVersionDefault = 1;
 #elif defined(OS_ANDROID)
 const uint64 kEmbeddedPageVersionDefault = 1;
 // Use this variant to enable EmbeddedSearch SearchBox API in the results page.
 const uint64 kEmbeddedSearchEnabledVersion = 2;
 #else
 const uint64 kEmbeddedPageVersionDefault = 2;
 #endif
 
 const char kHideVerbatimFlagName[] = "hide_verbatim";
-const char kPrefetchSearchResultsFlagName[] = "prefetch_results";
 const char kPrefetchSearchResultsOnSRP[] = "prefetch_results_srp";
 const char kAllowPrefetchNonDefaultMatch[] = "allow_prefetch_non_default_match";
 const char kPrerenderInstantUrlOnOmniboxFocus[] =
     "prerender_instant_url_on_omnibox_focus";
 
+#if defined(OS_ANDROID)
+const char kPrefetchSearchResultsFlagName[] = "prefetch_results";
+
 // Controls whether to reuse prerendered Instant Search base page to commit any
 // search query.
 const char kReuseInstantSearchBasePage[] = "reuse_instant_search_base_page";
+#endif
 
 // Controls whether to use the alternate Instant search base URL. This allows
 // experimentation of Instant search.
 const char kUseAltInstantURL[] = "use_alternate_instant_url";
 const char kAltInstantURLPath[] = "search";
 const char kAltInstantURLQueryParams[] = "&qbp=1";
 
 const char kDisplaySearchButtonFlagName[] = "display_search_button";
 const char kOriginChipFlagName[] = "origin_chip";
 #if !defined(OS_IOS) && !defined(OS_ANDROID)
@@ skipping 502 matching lines @@
 
 GURL GetSearchResultPrefetchBaseURL(Profile* profile) {
   return ShouldPrefetchSearchResults() ?
       GetInstantURL(profile, kDisableStartMargin, true) : GURL();
 }
 
 bool ShouldPrefetchSearchResults() {
   if (!IsInstantExtendedAPIEnabled())
     return false;
 
+#if defined(OS_ANDROID)
   if (CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kPrefetchSearchResults)) {
     return true;
   }
 
   FieldTrialFlags flags;
   return GetFieldTrialInfo(&flags) && GetBoolValueForFlagWithDefault(
       kPrefetchSearchResultsFlagName, false, flags);
+#endif
+  return true;

[Jered, 2014/07/14 16:18:27]

nit: It would be slightly clearer to write #else ... #endif around this return

[kmadhusu, 2014/07/14 19:37:15]

Done.

 }
 
 bool ShouldAllowPrefetchNonDefaultMatch() {
   if (!ShouldPrefetchSearchResults())
     return false;
 
   FieldTrialFlags flags;
   return GetFieldTrialInfo(&flags) && GetBoolValueForFlagWithDefault(
       kAllowPrefetchNonDefaultMatch, false, flags);
 }
 
 bool ShouldPrerenderInstantUrlOnOmniboxFocus() {
   if (!ShouldPrefetchSearchResults())
     return false;
 
   FieldTrialFlags flags;
   return GetFieldTrialInfo(&flags) && GetBoolValueForFlagWithDefault(
       kPrerenderInstantUrlOnOmniboxFocus, false, flags);
 }
 
 bool ShouldReuseInstantSearchBasePage() {
   if (!ShouldPrefetchSearchResults())
     return false;
 
+#if defined(OS_ANDROID)
   FieldTrialFlags flags;
   return GetFieldTrialInfo(&flags) && GetBoolValueForFlagWithDefault(
       kReuseInstantSearchBasePage, false, flags);
+#endif
+  return true;
 }
 
 GURL GetLocalInstantURL(Profile* profile) {
   return GURL(chrome::kChromeSearchLocalNtpUrl);
 }
 
 bool ShouldHideTopVerbatimMatch() {
   FieldTrialFlags flags;
   return GetFieldTrialInfo(&flags) && GetBoolValueForFlagWithDefault(
       kHideVerbatimFlagName, false, flags);
@@ skipping 215 matching lines @@
   return !!GetUInt64ValueForFlagWithDefault(flag, default_value ? 1 : 0, flags);
 }
 
 bool ShouldUseAltInstantURL() {
   FieldTrialFlags flags;
   return GetFieldTrialInfo(&flags) && GetBoolValueForFlagWithDefault(
       kUseAltInstantURL, false, flags);
 }
 
 }  // namespace chrome