Create a Lite Page bit for previews and fallback to Lo-Fi

chrome/browser/loader/chrome_resource_dispatcher_host_delegate.cc

 // 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.
 
 #include "chrome/browser/loader/chrome_resource_dispatcher_host_delegate.h"
 
 #include <stdint.h>
 #include <string>
 #include <utility>
 #include <vector>
@@ skipping 845 matching lines @@
                  base::TimeTicks::Now() - url_request->creation_time()));
 }
 
 content::PreviewsState ChromeResourceDispatcherHostDelegate::GetPreviewsState(
     const net::URLRequest& url_request,
     content::ResourceContext* resource_context) {
   ProfileIOData* io_data = ProfileIOData::FromResourceContext(resource_context);
   data_reduction_proxy::DataReductionProxyIOData* data_reduction_proxy_io_data =
       io_data->data_reduction_proxy_io_data();
 
-  if (data_reduction_proxy_io_data) {
-    return data_reduction_proxy_io_data->ShouldEnableLoFiMode(url_request)
-               ? content::SERVER_LOFI_ON
-               : content::PREVIEWS_OFF;
+  content::PreviewsState previews_state = content::PREVIEWS_UNSPECIFIED;

[bengr, 2017/02/15 00:03:47]

Why do you need separate values for UNSPECIFIED and OFF?

[megjablon, 2017/02/16 04:29:09]

For requesting the original page with previews off. When we do that set
PREVIEWS_OFF on the navigation request so that we don't call the code to get the
preview state here.

https://cs.chromium.org/chromium/src/content/browser/loader/resource_dispatch...

+
+  if (data_reduction_proxy_io_data &&

[bengr, 2017/02/15 00:03:47]

Style nit:

if (drp_io_data) {
  if (drp_io_data->ShouldEnableFoo(request)
    previews_state |= LOFI_ON;
  if (drp_io_data->ShouldEnableBar(request)
    previews_state |= LITE_PAGE_ON;

[megjablon, 2017/02/16 04:29:09]

Done.

+      data_reduction_proxy_io_data->ShouldEnableLoFi(url_request)) {
+    previews_state |= content::SERVER_LOFI_ON;
   }
-  return content::PREVIEWS_OFF;
+
+  if (data_reduction_proxy_io_data &&
+      data_reduction_proxy_io_data->ShouldEnableLitePages(url_request)) {
+    previews_state |= content::SERVER_LITE_PAGE_ON;
+  }
+
+  if (previews_state == content::PREVIEWS_UNSPECIFIED)
+    return content::PREVIEWS_OFF;
+  return previews_state;
 }
 
 // static
 void ChromeResourceDispatcherHostDelegate::
     SetExternalProtocolHandlerDelegateForTesting(
     ExternalProtocolHandler::Delegate* delegate) {
   g_external_protocol_handler_delegate = delegate;
 }
 
 content::NavigationData*
@@ skipping 33 matching lines @@
           base::Bind(&ChromeResourceDispatcherHostDelegate::OnAbortedFrameLoad,
                     base::Unretained(this), url, request_loading_time));
       return;
   }
 
   std::string metric_name = (request_loading_time.InMilliseconds() < 100 ?
       "Net.ErrAborted.Fast" : "Net.ErrAborted.Slow");
   rappor::SampleDomainAndRegistryFromGURL(
       g_browser_process->rappor_service(), metric_name, url);
 }