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..d749a587a0e713378fc3f23dba29f89d8ca07c9c 100644
--- a/third_party/WebKit/Source/platform/mhtml/MHTMLArchive.cpp
+++ b/third_party/WebKit/Source/platform/mhtml/MHTMLArchive.cpp
@@ -83,6 +83,19 @@ 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) {
+        const AtomicString& mimeType = resources[0]->mimeType();
+        if (MIMETypeRegistry::isSupportedNonImageMIMEType(mimeType)
+            || MIMETypeRegistry::isSupportedImageResourceMIMEType(mimeType)) {
+            archive->setMainResource(resources[0].get());
+        } else {
+            archive->addSubresource(resources[0].get());
+        }
+        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();