Add recommended extension installation support

extensions/browser/management_policy.h

Index: extensions/browser/management_policy.h
diff --git a/extensions/browser/management_policy.h b/extensions/browser/management_policy.h
index 149a598fc38527e595a2be38dc08475ea62694a8..a8578224f544ffc89c333fefbbf0d8d27dea4a8b 100644
--- a/extensions/browser/management_policy.h
+++ b/extensions/browser/management_policy.h
@@ -74,6 +74,11 @@ class ManagementPolicy {
                                     Extension::DisableReason* reason,
                                     base::string16* error) const;
 
+    // Similar to MustRemainEnabled, but for whether an extension must remain
+    // installed, and returns an error and/or reason if the caller needs it.
+    virtual bool MustRemainInstalled(const Extension* extension,
+                                     base::string16* error) const;
+
    private:
     DISALLOW_COPY_AND_ASSIGN(Provider);
   };
@@ -109,6 +114,11 @@ class ManagementPolicy {
                           Extension::DisableReason* reason,
                           base::string16* error) const;
 
+  // Returns true immediately if any registered provider's MustRemainInstalled
+  // function returns true.
+  bool MustRemainInstalled(const Extension* extension,
+                           base::string16* error) const;
+
   // For use in testing.
   void UnregisterAllProviders();
   int GetNumProviders() const;