Only generate suggested filenames when actually dragging an image.

third_party/WebKit/Source/core/loader/DocumentLoader.cpp

 /*
  * Copyright (C) 2006, 2007, 2008 Apple Inc. All rights reserved.
  * 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:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 422 matching lines @@
   //
   // TODO(mkwst):  Remove this once XFO moves to the browser.
   // https://crbug.com/555418.
   clearMainResourceHandle();
   m_contentSecurityPolicy.clear();
   KURL blockedURL = SecurityOrigin::urlWithUniqueSecurityOrigin();
   m_originalRequest.setURL(blockedURL);
   m_request.setURL(blockedURL);
   m_redirectChain.pop_back();
   appendRedirect(blockedURL);
-  m_response = ResourceResponse(blockedURL, "text/html", 0, nullAtom, String());
+  m_response = ResourceResponse(blockedURL, "text/html", 0, nullAtom);
   finishedLoading(monotonicallyIncreasingTime());
 
   return;
 }
 
 void DocumentLoader::responseReceived(
     Resource* resource,
     const ResourceResponse& response,
     std::unique_ptr<WebDataConsumerHandle> handle) {
   DCHECK_EQ(m_mainResource, resource);
@@ skipping 246 matching lines @@
   bool shouldLoadEmpty = !m_substituteData.isValid() &&
                          (m_request.url().isEmpty() ||
                           SchemeRegistry::shouldLoadURLSchemeAsEmptyDocument(
                               m_request.url().protocol()));
   if (!shouldLoadEmpty)
     return false;
 
   if (m_request.url().isEmpty() &&
       !frameLoader().stateMachine()->creatingInitialEmptyDocument())
     m_request.setURL(blankURL());
-  m_response =
-      ResourceResponse(m_request.url(), "text/html", 0, nullAtom, String());
+  m_response = ResourceResponse(m_request.url(), "text/html", 0, nullAtom);
   finishedLoading(monotonicallyIncreasingTime());
   return true;
 }
 
 void DocumentLoader::startLoadingMainResource() {
   timing().markNavigationStart();
   DCHECK(!m_mainResource);
   DCHECK_EQ(m_state, NotStarted);
   m_state = Provisional;
 
@@ skipping 92 matching lines @@
                              m_writer ? m_writer->encoding() : emptyAtom, true,
                              ForceSynchronousParsing);
   if (!source.isNull())
     m_writer->appendReplacingData(source);
   endWriting();
 }
 
 DEFINE_WEAK_IDENTIFIER_MAP(DocumentLoader);
 
 }  // namespace blink