Add support for Animated PNG

content/browser/loader/mime_sniffing_resource_handler.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 "content/browser/loader/mime_sniffing_resource_handler.h"
 
 #include <utility>
 #include <vector>
 
 #include "base/bind.h"
@@ skipping 29 matching lines @@
 #include "ppapi/features/features.h"
 #include "url/origin.h"
 
 namespace content {
 
 namespace {
 
 const char kAcceptHeader[] = "Accept";
 const char kFrameAcceptHeader[] =
     "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,"
-    "*/*;q=0.8";
+    "image/apng,*/*;q=0.8";

[scroggo_chromium, 2017/03/14 18:18:53]

japhet@ or kinuko@, could this change be causing the failures (e.g.
https://luci-logdog.appspot.com/v/?s=chromium%2Fbb%2Ftryserver.chromium.win%2...)
in http/tests/misc/xhtml.php
(https://cs.chromium.org/chromium/src/third_party/WebKit/LayoutTests/http/test...
)?

I haven't touched the "application/xhtml+xml" piece :-/

 const char kStylesheetAcceptHeader[] = "text/css,*/*;q=0.1";
-const char kImageAcceptHeader[] = "image/webp,image/*,*/*;q=0.8";
+const char kImageAcceptHeader[] = "image/webp,image/apng,image/*,*/*;q=0.8";
 const char kDefaultAcceptHeader[] = "*/*";
 
 // Used to write into an existing IOBuffer at a given offset.
 class DependentIOBuffer : public net::WrappedIOBuffer {
  public:
   DependentIOBuffer(net::IOBuffer* buf, int offset)
       : net::WrappedIOBuffer(buf->data() + offset), buf_(buf) {}
 
  private:
   ~DependentIOBuffer() override {}
@@ skipping 542 matching lines @@
 
 void MimeSniffingResourceHandler::OnPluginsLoaded(
     const std::vector<WebPluginInfo>& plugins) {
   // No longer blocking on the plugins being loaded.
   request()->LogUnblocked();
   if (state_ == STATE_BUFFERING)
     AdvanceState();
 }
 
 }  // namespace content