Merge pull request #1173 from Gregable/meta

AMP Validator. Whitelist new meta tag for amp-access.

validator/validator.protoascii

@@ -25,7 +25,7 @@ min_validator_revision_required: 67
 # newer versions of the spec file. This is currently a Google internal
 # mechanism, validator.js does not use this facility. However, any
 # change to this file requires updating this revision id.
-spec_file_revision: 98
+spec_file_revision: 99
 # Rules for AMP HTML
 # (https://github.com/google/amphtml/blob/master/spec/amp-html-format.md).
 # These rules are just enough to validate the example from the spec.
@@ -425,6 +425,24 @@ tags: {
     mandatory: true
   }
 }
+# AMP-specific extension:
+# Publishers may set this meta tag to indicate premium content. If present,
+# Google's AMP Cache will only serve this content when Referer is *.google.com.
+tags: {
+  name: "meta"
+  unique: true
+  mandatory_parent: "head"
+  attrs: {
+    name: "http-equiv"
+    mandatory: true
+    value: "amp-access"
+  }
+  attrs: {
+    name: "content"
+    mandatory: true
+    value: "premium"
+  }
+}
 # 4.2.6 The style
 # Text contents of the style tag will be validated seperately.
 tags: {  # Special custom 'author' spreadsheet.