Allow overriding variation parameter via chrome://flags.

chrome/browser/about_flags.h

 // 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.
 
 #ifndef CHROME_BROWSER_ABOUT_FLAGS_H_
 #define CHROME_BROWSER_ABOUT_FLAGS_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 16 matching lines @@
 }
 
 namespace about_flags {
 
 // Reads the state from |flags_storage| and adds the command line flags
 // belonging to the active feature entries to |command_line|.
 void ConvertFlagsToSwitches(flags_ui::FlagsStorage* flags_storage,
                             base::CommandLine* command_line,
                             flags_ui::SentinelsMode sentinels);
 
+// Registers variations parameter values stored in |flags_storage| (previously
+// selected in about:flags).
+void RegisterAllFeatureVariationParameters(
+    flags_ui::FlagsStorage* flags_storage);
+
 // Compares a set of switches of the two provided command line objects and
 // returns true if they are the same and false otherwise.
 // If |out_difference| is not NULL, it's filled with set_symmetric_difference
 // between sets.
 bool AreSwitchesIdenticalToCurrentCommandLine(
     const base::CommandLine& new_cmdline,
     const base::CommandLine& active_cmdline,
     std::set<base::CommandLine::StringType>* out_difference);
 
 // Gets the list of feature entries. Entries that are available for the current
@@ skipping 42 matching lines @@
 
 // This value is reported as switch histogram ID if switch name has unknown
 // format.
 extern const base::HistogramBase::Sample kBadSwitchFormatHistogramId;
 
 }  // namespace testing
 
 }  // namespace about_flags
 
 #endif  // CHROME_BROWSER_ABOUT_FLAGS_H_