Store PreRead options obtained from the registry in a global variable.

components/startup_metric_utils/common/pre_read_field_trial_utils_win.cc

 // Copyright 2015 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 "components/startup_metric_utils/common/pre_read_field_trial_utils_win.h"
 
 #include "base/callback.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/metrics/field_trial.h"
 #include "base/strings/string_util.h"
@@ skipping 17 matching lines @@
 // Variation names for the PreRead field trial.
 const base::char16 kNoPreReadVariationName[] = L"NoPreRead";
 const base::char16 kHighPriorityVariationName[] = L"HighPriority";
 const base::char16 kOnlyIfColdVariationName[] = L"OnlyIfCold";
 const base::char16 kPrefetchVirtualMemoryVariationName[] =
     L"PrefetchVirtualMemory";
 
 // Registry key in which the PreRead field trial group is stored.
 const base::char16 kPreReadFieldTrialRegistryKey[] = L"\\PreReadFieldTrial";
 
+// Pre-read options to use for the current process. This is initialized by
+// InitializePreReadOptions().
+PreReadOptions g_pre_read_options = {false, false, false, false};
+
 // Returns the registry path in which the PreRead group is stored.
 base::string16 GetPreReadRegistryPath(
     const base::string16& product_registry_path) {
   return product_registry_path + kPreReadFieldTrialRegistryKey;
 }
 
 }  // namespace
 
-void GetPreReadOptions(const base::string16& product_registry_path,
-                       bool* no_pre_read,
-                       bool* high_priority,
-                       bool* only_if_cold,
-                       bool* prefetch_virtual_memory) {
+void InitializePreReadOptions(const base::string16& product_registry_path) {
   DCHECK(!product_registry_path.empty());
-  DCHECK(no_pre_read);
-  DCHECK(high_priority);
-  DCHECK(only_if_cold);
-  DCHECK(prefetch_virtual_memory);
 
   // Open the PreRead field trial's registry key.
   const base::string16 registry_path =
       GetPreReadRegistryPath(product_registry_path);
   const base::win::RegKey key(HKEY_CURRENT_USER, registry_path.c_str(),
                               KEY_QUERY_VALUE);
 
   // Set the PreRead field trial's options.
-  struct VariationMapping {
+  struct {
     const base::char16* name;
-    bool* variable;
+    bool* option;
   } const variations_mappings[] = {
-      {kNoPreReadVariationName, no_pre_read},
-      {kHighPriorityVariationName, high_priority},
-      {kOnlyIfColdVariationName, only_if_cold},
-      {kPrefetchVirtualMemoryVariationName, prefetch_virtual_memory},
+      {kNoPreReadVariationName, &g_pre_read_options.no_pre_read},
+      {kHighPriorityVariationName, &g_pre_read_options.high_priority},
+      {kOnlyIfColdVariationName, &g_pre_read_options.only_if_cold},
+      {kPrefetchVirtualMemoryVariationName,
+       &g_pre_read_options.prefetch_virtual_memory},
   };
 
   for (const auto& mapping : variations_mappings) {
     // Set the option variable to true if the corresponding value is found in
     // the registry. Set to false otherwise (default behavior).
     DWORD value = 0;
-    *mapping.variable = key.ReadValueDW(mapping.name, &value) == ERROR_SUCCESS;
-    DCHECK(!*mapping.variable || value == 1);
+    if (key.ReadValueDW(mapping.name, &value) == ERROR_SUCCESS) {
+      DCHECK_EQ(1U, value);
+      DCHECK(!*mapping.option);
+      *mapping.option = true;
+    }
   }
 }
 
+PreReadOptions GetPreReadOptions() {
+  return g_pre_read_options;
+}
+
 void UpdatePreReadOptions(const base::string16& product_registry_path) {
   DCHECK(!product_registry_path.empty());
 
   const base::string16 registry_path =
       GetPreReadRegistryPath(product_registry_path);
 
   // Clear the experiment key. That way, when the trial is shut down, the
   // registry will be cleaned automatically. Also, this prevents variation
   // params from the previous group to stay in the registry when the group is
   // updated.
@@ skipping 44 matching lines @@
   base::string16 group;
   key.ReadValue(L"", &group);
 
   if (!group.empty()) {
     register_synthetic_field_trial.Run(kPreReadSyntheticFieldTrialName,
                                        base::UTF16ToUTF8(group));
   }
 }
 
 }  // namespace startup_metric_utils