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

content/public/common/previews_state.h

+// 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"
+#include "third_party/WebKit/public/platform/WebURLRequest.h"
+
+#define STATIC_ASSERT_PREVIEWS_ENUM(a, b)                   \
+  static_assert(static_cast<int>(a) == static_cast<int>(b), \
+                "mismatching enums: " #a)
+
+namespace content {
+
+// The Previews state which determines whether to request a Preview version of
+// the resource. Previews are optimizations that change the format and
+// content of web pages to improve data savings and / or performance. This enum
+// determines which Previews types to request.
+enum PreviewsState {
+  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
+                             // 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.
+  PREVIEWS_STATE_LAST = PREVIEWS_OFF
+};
+
+// Ensure that content::PreviewsState and blink::WebURLRequest::PreviewsState
+// are kept in sync.
+STATIC_ASSERT_PREVIEWS_ENUM(PREVIEWS_UNSPECIFIED,
+                            blink::WebURLRequest::PreviewsUnspecified);
+STATIC_ASSERT_PREVIEWS_ENUM(SERVER_LOFI_ON, blink::WebURLRequest::ServerLoFiOn);
+STATIC_ASSERT_PREVIEWS_ENUM(CLIENT_LOFI_ON, blink::WebURLRequest::ClientLoFiOn);
+STATIC_ASSERT_PREVIEWS_ENUM(PREVIEWS_OFF, blink::WebURLRequest::PreviewsOff);
+STATIC_ASSERT_PREVIEWS_ENUM(PREVIEWS_STATE_LAST,
+                            blink::WebURLRequest::PreviewsStateLast);
+
+}  // namespace content
+
+#endif  // CONTENT_PUBLIC_COMMON_PREVIEWS_TYPE_H_