blink: permissions: add plumbing to revoke permissions

public/platform/modules/permissions/WebPermissionClient.h

Index: public/platform/modules/permissions/WebPermissionClient.h
diff --git a/public/platform/modules/permissions/WebPermissionClient.h b/public/platform/modules/permissions/WebPermissionClient.h
index efc8811b81bb5f4f33b96c8a9b1edb567632bad7..9ac246c4a2fb9a4f09dfac5ffd3f7a6e7da31e97 100644
--- a/public/platform/modules/permissions/WebPermissionClient.h
+++ b/public/platform/modules/permissions/WebPermissionClient.h
@@ -11,7 +11,9 @@
 
 namespace blink {
 
+// WebPermissionQueryCallback is kept for backward compatibility
 using WebPermissionQueryCallback = WebCallbacks<WebPermissionStatus, void>;
+using WebPermissionCallback = WebPermissionQueryCallback;
 
 class WebPermissionObserver;
 class WebURL;
@@ -21,7 +23,10 @@ class WebURL;
 class WebPermissionClient {
 public:
     // Query the permission status of a given origin for a specific permission.
-    virtual void queryPermission(WebPermissionType, const WebURL&, WebPermissionQueryCallback*) { }
+    virtual void queryPermission(WebPermissionType, const WebURL&, WebPermissionCallback*) { }
+
+    // Revoke a specific permission for a given origin.
+    virtual void revokePermission(WebPermissionType, const WebURL&, WebPermissionCallback*) { }
 
     // Listen for permission changes for a given origin and inform the observer
     // when they happen. The observer is not owned by the WebPermissionClient.