Special case support for MHTML archives consisting of a single image.

third_party/WebKit/Source/platform/mhtml/MHTMLArchive.cpp

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 65 matching lines @@
     // For security reasons we only load MHTML pages from local URLs.
     if (!SchemeRegistry::shouldTreatURLSchemeAsLocal(url.protocol()))
         return nullptr;
 
     MHTMLParser parser(data);
     WillBeHeapVector<RefPtrWillBeMember<ArchiveResource>> resources = parser.parseArchive();
     if (resources.isEmpty())
         return nullptr; // Invalid MHTML file.
 
     RefPtrWillBeRawPtr<MHTMLArchive> archive = adoptRefWillBeNoop(new MHTMLArchive);
+    // Special case for single resource archives, in that case we will make an image
+    // the main resource.
+    if (resources.size() == 1) {
+        if (MIMETypeRegistry::isSupportedNonImageMIMEType(mimeType)

[Dmitry Titov, 2016/02/18 01:31:15]

I am not sure why you are checking for both non-image and image mime types. Is
there a reason to check for non-image ones here?

+            || MIMETypeRegistry::isSupportedImageResourceMIMEType(mimeType)) {
+            archive->setMainResource(resources[0].get());
+        } else {
+            archive->addSubresource(resources[0].get());

[Dmitry Titov, 2016/02/18 01:30:05]

Is there a need to add non-recognized mime type as subresource in this case? It
seems your snippet form the bug would just work, right?

+        }
+        return archive.release();
+    }
+
     // The first document suitable resource is the main resource of the top frame.
     for (size_t i = 0; i < resources.size(); ++i) {
         const AtomicString& mimeType = resources[i]->mimeType();
         if (archive->mainResource() || !MIMETypeRegistry::isSupportedNonImageMIMEType(mimeType) || MIMETypeRegistry::isSupportedJavaScriptMIMEType(mimeType) || mimeType == "text/css")
             archive->addSubresource(resources[i].get());
         else
             archive->setMainResource(resources[i].get());
     }
     return archive.release();
 }
@@ skipping 145 matching lines @@
 
 DEFINE_TRACE(MHTMLArchive)
 {
     visitor->trace(m_mainResource);
 #if ENABLE(OILPAN)
     visitor->trace(m_subresources);
 #endif
 }
 
 } // namespace blink