Add a "minimum_chrome_version" key to the manifest.

chrome/common/extensions/extension_constants.h

Index: chrome/common/extensions/extension_constants.h
diff --git a/chrome/common/extensions/extension_constants.h b/chrome/common/extensions/extension_constants.h
index a83c2d8ae207d369788fc91e7789072062ef45b9..4d9ef8419cfc9dc8642aee4e5ed3878c53bf683a 100644
--- a/chrome/common/extensions/extension_constants.h
+++ b/chrome/common/extensions/extension_constants.h
@@ -10,6 +10,7 @@ namespace extension_manifest_keys {
   extern const wchar_t* kAllFrames;
   extern const wchar_t* kBackground;
   extern const wchar_t* kBrowserAction;
+  extern const wchar_t* kMinimumChromeVersion;
   extern const wchar_t* kChromeURLOverrides;
   extern const wchar_t* kContentScripts;
   extern const wchar_t* kConvertedFromUserScript;
@@ -66,6 +67,7 @@ namespace extension_manifest_values {
 
 // Error messages returned from Extension::InitFromValue().
 namespace extension_manifest_errors {
+  extern const char* kChromeVersionTooLow;
   extern const char* kInvalidBrowserAction;
   extern const char* kInvalidChromeURLOverrides;
   extern const char* kInvalidContentScript;
@@ -84,6 +86,7 @@ namespace extension_manifest_errors {
   extern const char* kInvalidMatchCount;
   extern const char* kInvalidMatch;
   extern const char* kInvalidMatches;
+  extern const char* kInvalidMinimumChromeVersion;
   extern const char* kInvalidName;
   extern const char* kInvalidPlugins;
   extern const char* kInvalidPluginsPath;