Record Data Savings for Client-Side LoFi

third_party/WebKit/Source/core/loader/resource/ImageResource.cpp

 /*
     Copyright (C) 1998 Lars Knoll (knoll@mpi-hd.mpg.de)
     Copyright (C) 2001 Dirk Mueller (mueller@kde.org)
     Copyright (C) 2002 Waldo Bastian (bastian@kde.org)
     Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
     Copyright (C) 2004, 2005, 2006, 2007 Apple Inc. All rights reserved.
 
     This library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Library General Public
     License as published by the Free Software Foundation; either
@@ skipping 476 matching lines @@
 
   // Prevent clients and observers from being notified of completion while the
   // reload is being scheduled, so that e.g. canceling an existing load in
   // progress doesn't cause clients and observers to be notified of completion
   // prematurely.
   DCHECK(!is_scheduling_reload_);
   is_scheduling_reload_ = true;
 
   SetCachePolicyBypassingCache();
 
-  SetPreviewsStateNoTransform();
+  // The reloaded image should not use any previews transformations.
+  WebURLRequest::PreviewsState previews_state_for_reload =
+      WebURLRequest::kPreviewsNoTransform;
+
+  if (policy == kReloadIfNeeded && (GetResourceRequest().GetPreviewsState() &
+                                    WebURLRequest::kClientLoFiOn)) {
+    // If the image attempted to use Client LoFi, but encountered a decoding
+    // error and is being automatically reloaded, then also set the appropriate
+    // PreviewsState bit for that. This allows the embedder to count the
+    // bandwidth used for this reload against the data savings of the initial
+    // response.
+    previews_state_for_reload |= WebURLRequest::kClientLoFiAutoReload;
+  }
+  SetPreviewsState(previews_state_for_reload);
 
   if (placeholder_option_ != PlaceholderOption::kDoNotReloadPlaceholder)
     ClearRangeRequestHeader();
   placeholder_option_ = PlaceholderOption::kDoNotReloadPlaceholder;
 
   if (IsLoading()) {
     Loader()->Cancel();
     // Canceling the loader causes error() to be called, which in turn calls
     // clear() and notifyObservers(), so there's no need to call these again
     // here.
@@ skipping 91 matching lines @@
     //    reloading in Step 3 due to notifyObservers()'s
     //    schedulingReloadOrShouldReloadBrokenPlaceholder() check.
     // 3. reloadIfLoFiOrPlaceholderImage() is called via ResourceFetcher
     //    (a) via didFinishLoading() called in decodeError(), or
     //    (b) after returning ImageResource::updateImage().
     DecodeError(all_data_received);
   }
 }
 
 }  // namespace blink