Make the UI an observer of downloads.

content/browser/android/download_controller_android_impl.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/android/download_controller_android_impl.h"
 
 #include "base/android/jni_android.h"
 #include "base/android/jni_string.h"
 #include "base/bind.h"
 #include "base/logging.h"
@@ skipping 217 matching lines @@
   ScopedJavaLocalRef<jstring> jreferer =
       ConvertUTF8ToJavaString(env, info.referer);
 
   Java_DownloadController_newHttpGetDownload(
       env, GetJavaObject()->Controller(env).obj(), view.obj(), jurl.obj(),
       juser_agent.obj(), jcontent_disposition.obj(), jmime_type.obj(),
       jcookie.obj(), jreferer.obj(), info.total_bytes);
 }
 
 void DownloadControllerAndroidImpl::OnPostDownloadStarted(
-    WebContents* web_contents,
     DownloadItem* download_item) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  if (download_item->GetWebContents() == NULL)

[benjhayden, 2012/12/20 21:09:14]

I thought the convention was if (!GetWebContents())

[asanka, 2012/12/20 22:41:19]

Done.

+    return;
+
   JNIEnv* env = AttachCurrentThread();
 
   // Register for updates to the DownloadItem.
   download_item->AddObserver(this);
 
   ScopedJavaLocalRef<jobject> view =
-      GetContentViewCoreFromWebContents(web_contents);
+      GetContentViewCoreFromWebContents(download_item->GetWebContents());
   if(view.is_null()) {
     // The view went away. Can't proceed.
     return;
   }
 
   Java_DownloadController_onHttpPostDownloadStarted(
       env, GetJavaObject()->Controller(env).obj(), view.obj());
 }
 
 void DownloadControllerAndroidImpl::OnDownloadUpdated(DownloadItem* item) {
@@ skipping 89 matching lines @@
     referer = referer_url.spec();
   if (!request->url_chain().empty()) {
     original_url = request->url_chain().front();
     url = request->url_chain().back();
   }
 }
 
 DownloadControllerAndroidImpl::DownloadInfoAndroid::~DownloadInfoAndroid() {}
 
 }  // namespace content