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

chrome/browser/loader/chrome_resource_dispatcher_host_delegate.h

 // Copyright (c) 2012 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 CHROME_BROWSER_LOADER_CHROME_RESOURCE_DISPATCHER_HOST_DELEGATE_H_
 #define CHROME_BROWSER_LOADER_CHROME_RESOURCE_DISPATCHER_HOST_DELEGATE_H_
 
 #include <map>
 #include <memory>
 #include <set>
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "chrome/browser/external_protocol/external_protocol_handler.h"
 #include "content/public/browser/resource_dispatcher_host_delegate.h"
+#include "content/public/common/previews_state.h"
 #include "extensions/features/features.h"
 
 class DownloadRequestLimiter;
 
 namespace content {
 class NavigationData;
 }
 
 namespace extensions {
 class UserScriptListener;
@@ skipping 48 matching lines @@
   void OnStreamCreated(net::URLRequest* request,
                        std::unique_ptr<content::StreamInfo> stream) override;
   void OnResponseStarted(net::URLRequest* request,
                          content::ResourceContext* resource_context,
                          content::ResourceResponse* response) override;
   void OnRequestRedirected(const GURL& redirect_url,
                            net::URLRequest* request,
                            content::ResourceContext* resource_context,
                            content::ResourceResponse* response) override;
   void RequestComplete(net::URLRequest* url_request) override;
-  bool ShouldEnableLoFiMode(
+  content::PreviewsState GetPreviewsState(

[Nico, 2017/01/09 22:35:03]

I'm confused about this. The enum definition looks like the states are mutually
exclusive and this returns the enum and not an unsigned, yet the CL description
says "bitmask" and the checks use & instead of ==. Is this a bitmask, or no?

[megjablon, 2017/01/10 22:30:01]

The states aren't mutually exclusive. Server Lo-Fi and client Lo-Fi can both be
enabled at the same time. That's what this change is to help with. We need to
move Lo-Fi under Previews as a type, but also allow multiple previews types to
be set at once. This was initially an int, but nasko asked for me to use the
type, and I've seen it done both ways throughout the code. 

[Nico, 2017/01/11 01:14:47]

I think some integer type is more natural for a bit mask, but ok. Add a comment
"Returns bitmask of potentially several PreviewsState comment" then maybe.

[megjablon, 2017/01/12 17:56:29]

Done.

       const net::URLRequest& url_request,
       content::ResourceContext* resource_context) override;
   content::NavigationData* GetNavigationData(
       net::URLRequest* request) const override;
   std::unique_ptr<net::ClientCertStore> CreateClientCertStore(
       content::ResourceContext* resource_context) override;
   void OnAbortedFrameLoad(const GURL& url,
                           base::TimeDelta request_loading_time) override;
 
   // Called on the UI thread. Allows switching out the
@@ skipping 21 matching lines @@
   scoped_refptr<safe_browsing::SafeBrowsingService> safe_browsing_;
 #if BUILDFLAG(ENABLE_EXTENSIONS)
   scoped_refptr<extensions::UserScriptListener> user_script_listener_;
   std::map<net::URLRequest*, StreamTargetInfo> stream_target_info_;
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(ChromeResourceDispatcherHostDelegate);
 };
 
 #endif  // CHROME_BROWSER_LOADER_CHROME_RESOURCE_DISPATCHER_HOST_DELEGATE_H_