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

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

Index: third_party/WebKit/Source/platform/mhtml/MHTMLArchive.cpp
diff --git a/third_party/WebKit/Source/platform/mhtml/MHTMLArchive.cpp b/third_party/WebKit/Source/platform/mhtml/MHTMLArchive.cpp
index 4c8811dcaf0429650b643978e56a654098f0f6cd..7558f67abc7c8aa8d499c21c3d9e25fc6dc3f6b3 100644
--- a/third_party/WebKit/Source/platform/mhtml/MHTMLArchive.cpp
+++ b/third_party/WebKit/Source/platform/mhtml/MHTMLArchive.cpp
@@ -83,6 +83,18 @@ PassRefPtrWillBeRawPtr<MHTMLArchive> MHTMLArchive::create(const KURL& url, Share
         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();