Add support for --critical-update-version to installer.

chrome/installer/util/installer_state.h

Index: chrome/installer/util/installer_state.h
diff --git a/chrome/installer/util/installer_state.h b/chrome/installer/util/installer_state.h
index 04417be2dcf81bf39428b0b9db33e74b1a6ceb8c..987bf1b2276084ea8b6c88c4b5ebeb015af8c3f8 100644
--- a/chrome/installer/util/installer_state.h
+++ b/chrome/installer/util/installer_state.h
@@ -14,6 +14,7 @@
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/scoped_vector.h"
+#include "base/version.h"
 #include "chrome/installer/util/browser_distribution.h"
 #include "chrome/installer/util/product.h"
 #include "chrome/installer/util/util_constants.h"
@@ -144,6 +145,14 @@ class InstallerState {
   // products are installed.  Ownership is passed to the caller.
   Version* GetCurrentVersion(const InstallationState& machine_state) const;
 
+  // Returns the critical update version if all of the following are true:
+  // * --critical-update-version=CUV was specified on the command-line.
+  // * current_version == NULL or current_version < CUV.
+  // * new_version >= CUV.
+  // Otherwise, returns an invalid version.
+  Version DetermineCriticalVersion(const Version* current_version,
+                                   const Version& new_version) const;
+
   // Returns whether or not there is currently a Chrome Frame instance running.
   // Note that there isn't a mechanism to lock Chrome Frame in place, so Chrome
   // Frame may either exit or start up after this is called.
@@ -211,6 +220,7 @@ class InstallerState {
   BrowserDistribution::Type state_type_;
   ScopedVector<Product> products_;
   BrowserDistribution* multi_package_distribution_;
+  Version critical_update_version_;
   Level level_;
   PackageType package_type_;
 #if defined(OS_WIN)