Fix a bug where an extension's icon was not being properly updated.

chrome/common/extensions/extension.h

Index: chrome/common/extensions/extension.h
diff --git a/chrome/common/extensions/extension.h b/chrome/common/extensions/extension.h
index c000c808179bef3e2d40d054a191b74fc5b764ba..bddfa2650587d7f956944878edf1f1050866c696 100644
--- a/chrome/common/extensions/extension.h
+++ b/chrome/common/extensions/extension.h
@@ -310,6 +310,7 @@ class Extension : public base::RefCountedThreadSafe<Extension> {
   bool was_installed_by_default() const {
     return (creation_flags_ & WAS_INSTALLED_BY_DEFAULT) != 0;
   }
+  int image_id() const { return image_id_; }
 
   // App-related.
   bool is_app() const;
@@ -443,6 +444,10 @@ class Extension : public base::RefCountedThreadSafe<Extension> {
   // The flags that were passed to InitFromValue.
   int creation_flags_;
 
+  // The randomly generated ID used to identify if an image needs to be
+  // cached again when reloaded.
+  int image_id_;
+
   DISALLOW_COPY_AND_ASSIGN(Extension);
 };