Prerender: omnibox and instant field trial parameters.

chrome/browser/prerender/prerender_field_trial.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/prerender/prerender_field_trial.h"
 
 #include <string>
 
 #include "base/logging.h"
 #include "base/metrics/field_trial.h"
+#include "base/metrics/field_trial_params.h"
 #include "chrome/browser/prerender/prerender_manager.h"
 #include "chrome/common/chrome_switches.h"
-#include "components/variations/variations_associated_data.h"
 
 namespace prerender {
 
-// NoStatePrefetch feature modes, to control the PrerenderManager mode using
-// the base::Feature API and field trials.
+// NoStatePrefetch feature parameters, to control the PrerenderManager mode
+// using the base::Feature API and field trials.
+
+// The general prerender mode for most origins.
 const char kNoStatePrefetchFeatureModeParameterName[] = "mode";
+
+// Overriden prerender mode origins.

[pasko, 2017/03/17 17:33:33]

maybe s/origins/keys/ would make it more obvious that the values below are for
these keys? Maybe a bit more explanation how it works on the top?

really a nit, hopefully this code does not survive for long.

[mattcary, 2017/03/20 10:20:31]

Done.

+const char kNoStatePrefetchFeatureInstantModeParameterName[] = "instant_mode";
+const char kNoStatePrefetchFeatureOmniboxModeParameterName[] = "omnibox_mode";
+
+// Mode values.
 const char kNoStatePrefetchFeatureModeParameterPrefetch[] = "no_state_prefetch";
 const char kNoStatePrefetchFeatureModeParameterPrerender[] = "prerender";
 const char kNoStatePrefetchFeatureModeParameterSimpleLoad[] = "simple_load";
+const char kNoStatePrefetchFeatureModeParameterDisabled[] = "disabled";
 
 const base::Feature kNoStatePrefetchFeature{"NoStatePrefetch",
                                             base::FEATURE_ENABLED_BY_DEFAULT};
 
-void ConfigurePrerender() {
-  PrerenderManager::PrerenderManagerMode mode =
-      PrerenderManager::PRERENDER_MODE_ENABLED;
+PrerenderManager::PrerenderManagerMode ParsePrerenderMode(

[pasko, 2017/03/17 17:33:33]

if the function is not used outside this file, it should be in the anonymous
namespace

[mattcary, 2017/03/20 10:20:31]

Done.

+    const char* parameter_name,
+    PrerenderManager::PrerenderManagerMode default_mode) {
+  PrerenderManager::PrerenderManagerMode mode = default_mode;
   if (!base::FeatureList::IsEnabled(kNoStatePrefetchFeature)) {
     mode = PrerenderManager::PRERENDER_MODE_DISABLED;
   } else {
-    std::string mode_value = variations::GetVariationParamValueByFeature(
-        kNoStatePrefetchFeature, kNoStatePrefetchFeatureModeParameterName);
-    if (mode_value == kNoStatePrefetchFeatureModeParameterPrefetch) {
+    std::string mode_value = base::GetFieldTrialParamValueByFeature(

[pasko, 2017/03/17 17:33:33]

did you change the function solely because of deprecation of the old?

[mattcary, 2017/03/20 10:20:31]

Yup.

+        kNoStatePrefetchFeature, parameter_name);
+    if (mode_value.empty()) {
+      mode = default_mode;
+    } else if (mode_value == kNoStatePrefetchFeatureModeParameterPrefetch) {
       mode = PrerenderManager::PRERENDER_MODE_NOSTATE_PREFETCH;
-    } else if (mode_value.empty() ||
-               mode_value == kNoStatePrefetchFeatureModeParameterPrerender) {
-      // The empty string means the option was provided with no value, and that
-      // means enable.
+    } else if (mode_value == kNoStatePrefetchFeatureModeParameterPrerender) {
       mode = PrerenderManager::PRERENDER_MODE_ENABLED;
     } else if (mode_value == kNoStatePrefetchFeatureModeParameterSimpleLoad) {
       mode = PrerenderManager::PRERENDER_MODE_SIMPLE_LOAD_EXPERIMENT;
+    } else if (mode_value == kNoStatePrefetchFeatureModeParameterDisabled) {
+      mode = PrerenderManager::PRERENDER_MODE_DISABLED;
     } else {
-      LOG(ERROR) << "Invalid prerender mode: " << mode_value;
-      LOG(ERROR) << "Disabling prerendering!";
-      mode = PrerenderManager::PRERENDER_MODE_DISABLED;
+      LOG(ERROR) << "Invalid prerender mode: " << mode_value << " for "
+                 << parameter_name;
+      LOG(ERROR) << "Using default mode " << default_mode << " for "
+                 << parameter_name << "!";
+      mode = default_mode;
     }
   }
+  return mode;
+}
 
-  PrerenderManager::SetMode(mode);
+void ConfigurePrerender() {
+  PrerenderManager::PrerenderManagerMode overall_mode =
+      ParsePrerenderMode(kNoStatePrefetchFeatureModeParameterName,
+                         PrerenderManager::PRERENDER_MODE_ENABLED);
+
+  PrerenderManager::SetMode(overall_mode);
+  PrerenderManager::SetInstantMode(ParsePrerenderMode(
+      kNoStatePrefetchFeatureInstantModeParameterName, overall_mode));
+  PrerenderManager::SetOmniboxMode(ParsePrerenderMode(
+      kNoStatePrefetchFeatureOmniboxModeParameterName, overall_mode));
 }
 
 bool IsOmniboxEnabled(Profile* profile) {
   if (!profile)
     return false;
 
-  if (!PrerenderManager::IsPrerenderingPossible())
+  if (!PrerenderManager::IsAnyPrerenderingPossible())
     return false;
 
   // Override any field trial groups if the user has set a command line flag.
   if (base::CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kPrerenderFromOmnibox)) {
     const std::string switch_value =
         base::CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
             switches::kPrerenderFromOmnibox);
 
     if (switch_value == switches::kPrerenderFromOmniboxSwitchValueEnabled)
       return true;
 
     if (switch_value == switches::kPrerenderFromOmniboxSwitchValueDisabled)
       return false;
 
     DCHECK_EQ(switches::kPrerenderFromOmniboxSwitchValueAuto, switch_value);
   }
 
   return (base::FieldTrialList::FindFullName("PrerenderFromOmnibox") !=
           "OmniboxPrerenderDisabled");
 }
 
 }  // namespace prerender