Consistently use LoFi for an entire page

content/common/navigation_params.h

 // Copyright 2014 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_COMMON_NAVIGATION_PARAMS_H_
 #define CONTENT_COMMON_NAVIGATION_PARAMS_H_
 
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/time/time.h"
 #include "content/common/content_export.h"
 #include "content/common/frame_message_enums.h"
 #include "content/public/common/page_state.h"
 #include "content/public/common/referrer.h"
 #include "ui/base/page_transition_types.h"
 #include "url/gurl.h"
 
 namespace base {
 class RefCountedMemory;
 }
 
 namespace content {
 
+// The LoFi state which determines whether to add the LoFi header. Must stay in
+// sync with the enum in url_request.h.
+enum LoFiState {
+  // Add the LoFi header to the request.

[bengr, 2015/08/25 00:00:02]

I would make the comments more declarative, e.g.:

// Request a LoFi version of the resource.

// Request a normal (non-LoFi) version of the resource.

// Let the browser process decide whether or not to request the LoFi version.

[megjablon, 2015/08/25 20:29:46]

Done.

+  LOFI_ON = 0,
+  // Do not add the LoFi header to the request.
+  LOFI_OFF,
+  // Check with the network-quality-based triggering logic and add the header if
+  // the network is slow.
+  LOFI_DEFAULT,
+};
+
 // PlzNavigate
 // Helper function to determine if the navigation to |url| should make a request
 // to the network stack. A request should not be sent for data URLs, JavaScript
 // URLs or about:blank. In these cases, no request needs to be sent.
 bool ShouldMakeNetworkRequestForURL(const GURL& url);
 
 // The following structures hold parameters used during a navigation. In
 // particular they are used by FrameMsg_Navigate, FrameMsg_CommitNavigation and
 // FrameHostMsg_BeginNavigation.
 
@@ skipping 149 matching lines @@
                           base::Time request_time,
                           const PageState& page_state,
                           int32 page_id,
                           int nav_entry_id,
                           bool is_same_document_history_load,
                           bool has_committed_real_load,
                           bool intended_as_new_entry,
                           int pending_history_list_offset,
                           int current_history_list_offset,
                           int current_history_list_length,
-                          bool should_clear_history_list);
+                          bool should_clear_history_list,
+                          int lofi_state);
   ~RequestNavigationParams();
 
   // Whether or not the user agent override string should be used.
   bool is_overriding_user_agent;
 
   // The navigationStart time to expose through the Navigation Timing API to JS.
   base::TimeTicks browser_navigation_start;
 
   // Any redirect URLs that occurred before |url|. Useful for cross-process
   // navigations; defaults to empty.
@@ skipping 45 matching lines @@
 
   // Where its current page contents reside in session history and the total
   // size of the session history list.
   int current_history_list_offset;
   int current_history_list_length;
 
   // Whether session history should be cleared. In that case, the RenderView
   // needs to notify the browser that the clearing was succesful when the
   // navigation commits.
   bool should_clear_history_list;
+
+  // Whether or not the LoFi header should be added to the request or if the

[bengr, 2015/08/25 00:00:02]

Not necessary or desirable imho to describe how LoFi is requested. 

[megjablon, 2015/08/25 20:29:46]

Done.

+  // decision should be left up to the network-quality-based triggering logic.
+  int lofi_state;
 };
 
 // Helper struct keeping track in one place of all the parameters the browser
 // needs to provide to the renderer.
 struct NavigationParams {
   NavigationParams(const CommonNavigationParams& common_params,
                    const StartNavigationParams& start_params,
                    const RequestNavigationParams& request_params);
   ~NavigationParams();
 
   CommonNavigationParams common_params;
   StartNavigationParams start_params;
   RequestNavigationParams request_params;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_COMMON_NAVIGATION_PARAMS_H_