Observe adding external extensions via windows registry.

extensions/browser/external_provider_interface.h

Index: extensions/browser/external_provider_interface.h
diff --git a/extensions/browser/external_provider_interface.h b/extensions/browser/external_provider_interface.h
index 801f4ede5640de99259898da3c2b0e22cbb9e336..19102c045e2cf0285e1cd5d5fd6a51f542f4399a 100644
--- a/extensions/browser/external_provider_interface.h
+++ b/extensions/browser/external_provider_interface.h
@@ -13,12 +13,14 @@
 class GURL;
 
 namespace base {
-class FilePath;
 class Version;
 }
 
 namespace extensions {
 
+struct ExternalInstallInfoFile;
+struct ExternalInstallInfoUpdateUrl;
+
 // This class is an abstract class for implementing external extensions
 // providers.
 class ExternalProviderInterface {
@@ -35,24 +37,14 @@ class ExternalProviderInterface {
     // proceed if the extension is already installed from a higher priority
     // location.
     virtual bool OnExternalExtensionFileFound(
-        const std::string& id,
-        const base::Version* version,
-        const base::FilePath& path,
-        Manifest::Location location,
-        int creation_flags,
-        bool mark_acknowledged,
-        bool install_immediately) = 0;
+        const ExternalInstallInfoFile& info) = 0;
 
     // Return true if the extension install will proceed.  Install might not
     // proceed if the extension is already installed from a higher priority
     // location.
     virtual bool OnExternalExtensionUpdateUrlFound(
-        const std::string& id,
-        const std::string& install_parameter,
-        const GURL& update_url,
-        Manifest::Location location,
-        int creation_flags,
-        bool mark_acknowledged) = 0;
+        const ExternalInstallInfoUpdateUrl& info,
+        bool is_initial_load) = 0;
 
     // Called after all the external extensions have been reported
     // through the above two methods. |provider| is a pointer to the
@@ -62,6 +54,17 @@ class ExternalProviderInterface {
     virtual void OnExternalProviderReady(
         const ExternalProviderInterface* provider) = 0;
 
+    // Once this provider becomes "ready", it can send additional external
+    // extensions it learns about later on through
+    // OnExternalExtensionUpdateUrlFound() or OnExternalExtensionFileFound().
+    // This method will be called each time the provider finds a set of
+    // updated external extensions.
+    virtual void OnExternalProviderUpdateComplete(
+        const ExternalProviderInterface* provider,
+        const ScopedVector<ExternalInstallInfoUpdateUrl>& update_url_extensions,
+        const ScopedVector<ExternalInstallInfoFile>& file_extensions,
+        const std::set<std::string>& removed_extensions) = 0;
+
    protected:
     virtual ~VisitorInterface() {}
   };