[Downloads] Always call DM::StartDownload() for explicit downloads.

content/browser/download/drag_download_file.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/download/drag_download_file.h"
 
 #include "base/bind.h"
 #include "base/message_loop/message_loop.h"
 #include "content/browser/download/download_stats.h"
 #include "content/browser/web_contents/web_contents_impl.h"
@@ skipping 74 matching lines @@
  private:
   virtual ~DragDownloadFileUI() {
     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
     if (download_item_)
       download_item_->RemoveObserver(this);
   }
 
   void OnDownloadStarted(DownloadItem* item,
                          DownloadInterruptReason interrupt_reason) {
     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-    if (!item) {
-      DCHECK_NE(DOWNLOAD_INTERRUPT_REASON_NONE, interrupt_reason);
+    if (interrupt_reason != DOWNLOAD_INTERRUPT_REASON_NONE) {
       on_completed_loop_->PostTask(FROM_HERE, base::Bind(on_completed_, false));
       return;
     }
-    DCHECK_EQ(DOWNLOAD_INTERRUPT_REASON_NONE, interrupt_reason);
     download_item_ = item;
     download_item_->AddObserver(this);
   }
 
   // DownloadItem::Observer:
   virtual void OnDownloadUpdated(DownloadItem* item) OVERRIDE {
     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
     DCHECK_EQ(download_item_, item);
     DownloadItem::DownloadState state = download_item_->GetState();
     if (state == DownloadItem::COMPLETE ||
@@ skipping 123 matching lines @@
 
 void DragDownloadFile::CheckThread() {
 #if defined(OS_WIN)
   DCHECK(drag_message_loop_ == base::MessageLoop::current());
 #else
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 #endif
 }
 
 }  // namespace content