Added DownloadProcessHandle class.

chrome/browser/download/download_process_handle.cc

+// Copyright (c) 2011 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 "chrome/browser/download/download_process_handle.h"
+
+#include <string>
+
+#include "base/file_util.h"
+#include "base/stringprintf.h"
+#include "chrome/browser/download/download_manager.h"
+#include "chrome/browser/download/download_util.h"
+#include "chrome/browser/profiles/profile.h"
+#include "chrome/browser/tab_contents/tab_util.h"
+#include "content/browser/browser_thread.h"
+#include "content/browser/renderer_host/resource_dispatcher_host.h"
+#include "content/browser/tab_contents/tab_contents.h"
+
+DownloadProcessHandle::DownloadProcessHandle()
+    : child_id_(-1), render_view_id_(-1), request_id_(-1) {

[Randy Smith (Not in Mondays), 2011/05/05 20:25:34]

I believe it's invalid to call any of the routines in this with a default
constructed DownloadProcessHandle.  Can you put in DCHECKs for that case?  Under
what circumstances can we end up in the download system with an invalid
DownloadProcessHandle, and what happens if we need to do one of the below
operations on it in that case?

[ahendrickson, 2011/05/06 16:16:50]

In unit tests we call them with -1's; this just makes the GetTabContents
function return NULL.

I believe you have an invalid DFH when a DownloadItem is loaded from the history
database.  Not sure about Drag & Drop or Save Page As.

Waiting to get resolution on whether or not to have Cancel/Pause/Resume Download
in this class.

+}
+
+DownloadProcessHandle::DownloadProcessHandle(int child_id,
+                                             int render_view_id,
+                                             int request_id)
+    : child_id_(child_id),
+      render_view_id_(render_view_id),
+      request_id_(request_id) {
+}
+
+void DownloadProcessHandle::CancelDownload(ResourceDispatcherHost* rdh) {
+  BrowserThread::PostTask(
+      BrowserThread::IO, FROM_HERE,
+      NewRunnableFunction(&download_util::CancelDownloadRequest,
+                          rdh,
+                          child_id_,
+                          request_id_));
+}
+
+TabContents* DownloadProcessHandle::GetTabContents() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  return tab_util::GetTabContentsByID(child_id_, render_view_id_);
+}
+
+DownloadManager* DownloadProcessHandle::GetDownloadManager() {
+  TabContents* contents = GetTabContents();
+  if (!contents)
+    return NULL;
+
+  Profile* profile = contents->profile();
+  if (!profile)
+    return NULL;
+
+  return profile->GetDownloadManager();
+}