WebRequest API should warn when a developer attempts to filter URLs without proper permissions

Warn user if he attempts to register a web request filter without having any
host permissions for the extension. We don't try a full subsumption test (you
may register for a broader set of URLs than you have host permissions). This is
just a simple check that you have any host permissions at all, which should
help a careless developer to see his problem.

BUG=104435
TEST=no


Review URL: http://codereview.chromium.org/8931006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@114289 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/extensions/extension_webrequest_api.cc

@@ -1535,6 +1535,17 @@ bool WebRequestAddEventListener::RunImpl() {
     return false;
   }
 
+  // We allow to subscribe to patterns that are broader than the host
+  // permissions. E.g., we could subscribe to http://www.example.com/*
+  // while having host permissions for http://www.example.com/foo/* and
+  // http://www.example.com/bar/*.
+  // For this reason we do only a coarse check here to warn the extension
+  // developer if he does something obviously wrong.
+  if (extension->GetEffectiveHostPermissions().is_empty()) {
+    error_ = keys::kHostPermissionsRequired;
+    return false;
+  }
+
   ExtensionWebRequestEventRouter::GetInstance()->AddEventListener(
       profile_id(), extension_id(), extension_name,
       event_name, sub_event_name, filter,

chrome/browser/extensions/extension_webrequest_api_constants.cc

@@ -51,8 +51,11 @@ const char kInvalidBlockingResponse[] =
     "cancel cannot be true in the presence of other keys.";
 const char kInvalidRequestFilterUrl[] = "'*' is not a valid URL pattern.";
 const char kBlockingPermissionRequired[] =
-        "You do not have permission to use blocking webRequest listeners. "
-        "Be sure to declare the webRequestBlocking permission in your "
-        "manifest.";
+    "You do not have permission to use blocking webRequest listeners. "
+    "Be sure to declare the webRequestBlocking permission in your "
+    "manifest.";
+const char kHostPermissionsRequired[] =
+    "You need to request host permissions in the manifest file in order to "
+    "be notified about requests from the webRequest API.";
 
 }  // namespace extension_webrequest_api_constants

chrome/browser/extensions/extension_webrequest_api_constants.h

@@ -57,6 +57,7 @@ extern const char kInvalidRedirectUrl[];
 extern const char kInvalidBlockingResponse[];
 extern const char kInvalidRequestFilterUrl[];
 extern const char kBlockingPermissionRequired[];
+extern const char kHostPermissionsRequired[];
 
 }  // namespace extension_webrequest_api_constants