I'm expanding this to fix a couple of bugs in determining the file name for...

third_party/WebKit/WebCore/platform/chromium/ClipboardChromium.cpp

Index: third_party/WebKit/WebCore/platform/chromium/ClipboardChromium.cpp
===================================================================
--- third_party/WebKit/WebCore/platform/chromium/ClipboardChromium.cpp	(revision 10151)
+++ third_party/WebKit/WebCore/platform/chromium/ClipboardChromium.cpp	(working copy)
@@ -268,13 +268,14 @@
     // use the alt tag if one exists, otherwise we fall back on the suggested
     // filename in the http header, and finally we resort to using the filename
     // in the URL.
-    dataObject->fileExtension = ".";
-    dataObject->fileExtension += MIMETypeRegistry::getPreferredExtensionForMIMEType(
-        cachedImage->response().mimeType());
+    String extension = MIMETypeRegistry::getPreferredExtensionForMIMEType(
+        cachedImage->response().mimeType());
+    dataObject->fileExtension = extension.isEmpty() ? "" : "." + extension;
     String title = element->getAttribute(altAttr);
-    if (title.isEmpty()) {
+    if (title.isEmpty())
         title = cachedImage->response().suggestedFilename();
-    }
+
+    title = ClipboardChromium::validateFileName(title, dataObject);
     dataObject->fileContentFilename = title + dataObject->fileExtension;
 }