Return Windows error code when create-process fails.

chrome/installer/mini_installer/configuration.h

Index: chrome/installer/mini_installer/configuration.h
diff --git a/chrome/installer/mini_installer/configuration.h b/chrome/installer/mini_installer/configuration.h
index 1c75960d693acafad61d44912c92b87c36d81067..605fa907a2e8bc918d3e8be2c04c20c7758aaab6 100644
--- a/chrome/installer/mini_installer/configuration.h
+++ b/chrome/installer/mini_installer/configuration.h
@@ -7,6 +7,8 @@
 
 #include <windows.h>
 
+#include "chrome/installer/mini_installer/mini_string.h"
+
 namespace mini_installer {
 
 // A simple container of the mini_installer's configuration, as dictated by the
@@ -54,6 +56,9 @@ class Configuration {
   // Returns true if --system-level is on the command line.
   bool is_system_level() const { return is_system_level_; }
 
+  // Retuns true if --chrome-sxs is on the command line.
+  bool is_side_by_side() const { return is_side_by_side_; }
+
   // Returns the previous version contained in the image's resource.
   const wchar_t* previous_version() const { return previous_version_; }
 
@@ -71,11 +76,22 @@ class Configuration {
   bool has_chrome_frame_;
   bool is_multi_install_;
   bool is_system_level_;
+  bool is_side_by_side_;
   const wchar_t* previous_version_;
 
+ protected:
+  typedef StackString<128> ValueString;
+
+  // Virtual for testing.
+  virtual bool ReadClientStateRegistryValue(
+      const HKEY root_key, const wchar_t* app_guid,
+      LONG* retval, ValueString& value);
+
  private:
   Configuration(const Configuration&);
   Configuration& operator=(const Configuration&);
+
+  void SetChromeAppGuid();
 };
 
 }  // namespace mini_installer