Change Lo-Fi bool to bitmask to support multiple Previews types

content/public/common/previews_state.h

Index: content/public/common/previews_state.h
diff --git a/content/public/common/previews_state.h b/content/public/common/previews_state.h
new file mode 100644
index 0000000000000000000000000000000000000000..8bff7db6354c7dac86a03347567372a6f45b512c
--- /dev/null
+++ b/content/public/common/previews_state.h
@@ -0,0 +1,27 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CONTENT_PUBLIC_COMMON_PREVIEWS_TYPE_H_
+#define CONTENT_PUBLIC_COMMON_PREVIEWS_TYPE_H_
+
+#include "content/common/content_export.h"
+
+namespace content {
+
+// The Previews state which determines whether to request a Preview version of
+// the resource.

[nasko, 2016/12/08 22:19:33]

Please explain a bit more what Previews is. As it is, the comment doesn't give
me a good idea of what it is.
Alternatively, point to a publicly accessible design document explaining the
concept.

[megjablon, 2016/12/09 20:35:55]

I added the description we use elsewhere. There isn't a public design doc, and
since I'm not the owner I can't change the access. 

+enum PreviewsState {

[nasko, 2016/12/08 22:19:33]

Honestly, Previews does not convey to me the meaning of what LoFi does.

[megjablon, 2016/12/09 20:35:55]

Lo-Fi is a type of Preview. Lo-Fi used to be the only optimization of it's kind,
but we're working on other page optimizations that all fit into this same
category. Previews are optimizations that change the format and content of web
pages to improve data savings and / or performance. They can be applied
individually or in combination. This enum will soon include Lite Pages, which
are currently just using the Lo-Fi bool, but should be considered their own
optimization. Other preview types will also be showing an offline page on slow
connections and possibly javascript disable. 

+  PREVIEWS_UNSPECIFIED = 0,  // Let the browser process decide whether or
+                             // not to request Preview types.
+  SERVER_LOFI_ON = 1 << 0,   // Request a Lo-Fi version of the resource

[nasko, 2016/12/08 22:19:33]

Shouldn't the members be named using Previews instead of LoFi? Having both names
commingled leads to confusion.

[megjablon, 2016/12/09 20:35:55]

These are the previews types that can be applied individually or in combination.

+                             // from the server.
+  CLIENT_LOFI_ON = 1 << 1,   // Request a Lo-Fi version of the resource
+                             // from the client.
+  PREVIEWS_OFF = 1 << 2      // Request a normal (non-Preview) version of
+                             // the resource.
+};
+
+}  // namespace content
+
+#endif  // CONTENT_PUBLIC_COMMON_PREVIEWS_TYPE_H_