Improved performance of fetching variation parameters in AutomaticProfileResetter.

chrome/browser/profile_resetter/automatic_profile_resetter.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 "chrome/browser/profile_resetter/automatic_profile_resetter.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/logging.h"
 #include "base/memory/ref_counted.h"
@@ skipping 115 matching lines @@
       kAutomaticProfileResetStudyDryRunGroupName, true);
 }
 
 // Returns whether or not a live-run shall be performed.
 bool ShouldPerformLiveRun() {
   return StartsWithASCII(
       base::FieldTrialList::FindFullName(kAutomaticProfileResetStudyName),
       kAutomaticProfileResetStudyEnabledGroupName, true);
 }
 
-// Returns whether or not the currently active experiment group prescribes the
-// program and hash seed to use instead of the baked-in ones.
-bool DoesExperimentOverrideProgramAndHashSeed() {
+// If the currently active experiment group prescribes a |program| and
+// |ħash_seed| to use instead of the baked-in ones, retrieves those and returns

[Alexei Svitkine (slow), 2013/11/06 17:30:29]

Nit: Is the 'h' in hash_seed some accented one here (ħ), instead of the regular
one (h)?

[engedy, 2013/11/06 18:14:28]

Wow, I have no idea how that happened. Thanks for spotting it.

+// true. Otherwise, returns false.
+bool GetProgramAndHashSeedOverridesFromExperiment(std::string* program,
+                                                  std::string* hash_seed) {
+  DCHECK(program);
+  DCHECK(hash_seed);
 #if defined(GOOGLE_CHROME_BUILD)
   std::map<std::string, std::string> params;
   chrome_variations::GetVariationParams(kAutomaticProfileResetStudyName,
                                         &params);
-  return params.count(kAutomaticProfileResetStudyProgramParameterName) &&
-         params.count(kAutomaticProfileResetStudyHashSeedParameterName);
-#else
+  if (params.count(kAutomaticProfileResetStudyProgramParameterName) &&
+      params.count(kAutomaticProfileResetStudyHashSeedParameterName)) {
+    program->swap(params[kAutomaticProfileResetStudyProgramParameterName]);
+    hash_seed->swap(params[kAutomaticProfileResetStudyHashSeedParameterName]);
+    return true;
+  }
+#endif
   return false;
-#endif
 }
 
 // Deep-copies all preferences in |source| to a sub-tree named |value_tree_key|
 // in |target_dictionary|, with path expansion, and also creates an isomorphic
 // sub-tree under the key |is_user_controlled_tree_key| that contains only
 // Boolean values, indicating whether or not the corresponding preferences are
 // coming from the 'user' PrefStore.
 void BuildSubTreesFromPreferences(const PrefService* source,
                                   const char* value_tree_key,
                                   const char* is_user_controlled_tree_key,
@@ skipping 44 matching lines @@
 
 void AutomaticProfileResetter::Initialize() {
   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
   DCHECK_EQ(state_, STATE_UNINITIALIZED);
 
   if (!ShouldPerformDryRun() && !ShouldPerformLiveRun()) {
     state_ = STATE_DISABLED;
     return;
   }
 
-  ui::ResourceBundle& resources(ui::ResourceBundle::GetSharedInstance());
-  if (DoesExperimentOverrideProgramAndHashSeed()) {
-    program_ = chrome_variations::GetVariationParamValue(
-        kAutomaticProfileResetStudyName,
-        kAutomaticProfileResetStudyProgramParameterName);
-    hash_seed_ = chrome_variations::GetVariationParamValue(
-        kAutomaticProfileResetStudyName,
-        kAutomaticProfileResetStudyHashSeedParameterName);
-  } else if (ShouldPerformLiveRun()) {
-    program_ = resources.GetRawDataResource(
-        IDR_AUTOMATIC_PROFILE_RESET_RULES).as_string();
-    hash_seed_ = resources.GetRawDataResource(
-        IDR_AUTOMATIC_PROFILE_RESET_HASH_SEED).as_string();
-  } else {  // ShouldPerformDryRun()
-    program_ = resources.GetRawDataResource(
-        IDR_AUTOMATIC_PROFILE_RESET_RULES_DRY).as_string();
-    hash_seed_ = resources.GetRawDataResource(
-        IDR_AUTOMATIC_PROFILE_RESET_HASH_SEED_DRY).as_string();
+  if (!GetProgramAndHashSeedOverridesFromExperiment(&program_, &hash_seed_)) {
+    ui::ResourceBundle& resources(ui::ResourceBundle::GetSharedInstance());
+    if (ShouldPerformLiveRun()) {
+      program_ = resources.GetRawDataResource(
+          IDR_AUTOMATIC_PROFILE_RESET_RULES).as_string();
+      hash_seed_ = resources.GetRawDataResource(
+          IDR_AUTOMATIC_PROFILE_RESET_HASH_SEED).as_string();
+    } else {  // ShouldPerformDryRun()
+      program_ = resources.GetRawDataResource(
+          IDR_AUTOMATIC_PROFILE_RESET_RULES_DRY).as_string();
+      hash_seed_ = resources.GetRawDataResource(
+          IDR_AUTOMATIC_PROFILE_RESET_HASH_SEED_DRY).as_string();
+    }
   }
 
   delegate_.reset(new AutomaticProfileResetterDelegateImpl(
       TemplateURLServiceFactory::GetForProfile(profile_)));
   task_runner_for_waiting_ =
       content::BrowserThread::GetMessageLoopProxyForThread(
           content::BrowserThread::UI);
 
   state_ = STATE_INITIALIZED;
 }
@@ skipping 238 matching lines @@
                             kCombinedStatusMaskMaximumValue);
 }
 
 void AutomaticProfileResetter::Shutdown() {
   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
 
   state_ = STATE_DISABLED;
   delegate_.reset();
   weak_ptr_factory_.InvalidateWeakPtrs();
 }