Simulate variation seeds using installed version string.

chrome/browser/upgrade_detector_impl.h

Index: chrome/browser/upgrade_detector_impl.h
===================================================================
--- chrome/browser/upgrade_detector_impl.h	(revision 278434)
+++ chrome/browser/upgrade_detector_impl.h	(working copy)
@@ -7,6 +7,7 @@
 
 #include "base/memory/weak_ptr.h"
 #include "base/timer/timer.h"
+#include "base/version.h"
 #include "chrome/browser/upgrade_detector.h"
 
 template <typename T> struct DefaultSingletonTraits;
@@ -15,6 +16,11 @@
  public:
   virtual ~UpgradeDetectorImpl();
 
+  // Returns the currently installed Chrome version, which may be newer than the
+  // one currently running. Not supported on Android, iOS or ChromeOS. Must be
+  // run on a thread where I/O operations are allowed (e.g. FILE thread).
+  static base::Version GetCurrentlyInstalledVersion();
+
   // Returns the singleton instance.
   static UpgradeDetectorImpl* GetInstance();