Introduce WebRequestResourceType.

extensions/browser/api/web_request/web_request_resource_type.h

+// Copyright 2017 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 EXTENSIONS_BROWSER_API_WEB_REQUEST_WEB_REQUEST_RESOURCE_TYPE_H_
+#define EXTENSIONS_BROWSER_API_WEB_REQUEST_WEB_REQUEST_RESOURCE_TYPE_H_
+
+#include "content/public/common/resource_type.h"
+
+namespace extensions {
+
+// Enumerates all resource/request types that WebRequest API cares about.
+enum class WebRequestResourceType {
+  // Below are content::ResourceType values. Note: Each content::RESOURCE_TYPE_*
+  // is typed explicitly in order to catch if some of those values get deleted.
+  MAIN_FRAME = content::RESOURCE_TYPE_MAIN_FRAME,
+  SUB_FRAME = content::RESOURCE_TYPE_SUB_FRAME,
+  STYLESHEET = content::RESOURCE_TYPE_STYLESHEET,
+  SCRIPT = content::RESOURCE_TYPE_SCRIPT,
+  IMAGE = content::RESOURCE_TYPE_IMAGE,
+  FONT_RESOURCE = content::RESOURCE_TYPE_FONT_RESOURCE,
+  SUB_RESOURCE = content::RESOURCE_TYPE_SUB_RESOURCE,
+  OBJECT = content::RESOURCE_TYPE_OBJECT,
+  MEDIA = content::RESOURCE_TYPE_MEDIA,
+  WORKER = content::RESOURCE_TYPE_WORKER,
+  SHARED_WORKER = content::RESOURCE_TYPE_SHARED_WORKER,
+  PREFETCH = content::RESOURCE_TYPE_PREFETCH,
+  FAVICON = content::RESOURCE_TYPE_FAVICON,
+  XHR = content::RESOURCE_TYPE_XHR,
+  PING = content::RESOURCE_TYPE_PING,
+  SERVICE_WORKER = content::RESOURCE_TYPE_SERVICE_WORKER,
+  CSP_REPORT = content::RESOURCE_TYPE_CSP_REPORT,
+  PLUGIN_RESOURCE = content::RESOURCE_TYPE_PLUGIN_RESOURCE,
+
+  // Types of requests not in content::ResourceType.
+  WEBSOCKET,

[Devlin, 2017/02/16 15:13:05]

nit: Why WEBSOCKET instead of WEB_SOCKET?  (If this is more consistent with
another place, then it's fine but strikes me as a little odd)

[pkalinnikov, 2017/02/16 15:52:45]

Changed to WEB_SOCKET.

+
+  LAST_TYPE,
+};
+
+static_assert(content::RESOURCE_TYPE_LAST_TYPE ==
+                  content::RESOURCE_TYPE_PLUGIN_RESOURCE + 1,
+              "content::ResourceType has been modified.");
+
+inline WebRequestResourceType ToWebRequestResourceType(

[Devlin, 2017/02/16 15:13:05]

When we begin intercepting WebSocket requests, this in and of itself won't be
able to determine the resource type.  I wonder if it makes sense to have this
take a net::URLRequest* instead, so we can determine based on both type and url?

Something like:
WebRequestResourceType ToWebRequestResourceType(
    net::URLRequest* request) {
  if (request->url().SchemeIsWSOrWSS())
    return WebRequestResourceType::WEBSOCKET;
  content::ResourceRequestInfo* info =
      content::ResourceRequestInfo::ForRequest(request);
  if (!info)  // Not sure we need this...
    return WebRequestResourceType::LAST_TYPE;
  content::ResourceType content_resource_type = info->GetResourceType();
  return type == content::RESOURCE_TYPE_LAST_TYPE
      ? WebRequestResourceType::LAST_TYPE
      : static_cast<WebRequestResourceType>(type);
}

WDYT?  Otherwise, it seems like we'll need special handling before we call
ToWebRequestResourceType(), and I'd prefer to centralize the conversion logic in
one place.

[pkalinnikov, 2017/02/16 15:52:45]

I had been thinking about this as well, but I had 2 concerns:
 - A enum header knows about URLRequest (probably it's okay)
 - ResourceRequestInfo is already retrieved in the call site, so getting it in
ToWebRequestResourceType adds a bit of overhead. I could make a function that
takes ResourceRequestInfo as a parameter, though.

I am reluctant to remove the original ToWebRequestResourceType function, because
it still seems handy when there is no URLRequest nearby (e.g., in
IsRelevantResourceType function).

Let's add both functions and see in the follow-up CL if it's possible to get rid
of the original.

+    content::ResourceType type) {
+  return type == content::RESOURCE_TYPE_LAST_TYPE
+             ? WebRequestResourceType::LAST_TYPE
+             : static_cast<WebRequestResourceType>(type);
+}
+
+}  // namespace extensions
+
+#endif  // EXTENSIONS_BROWSER_API_WEB_REQUEST_WEB_REQUEST_RESOURCE_TYPE_H_