Added DownloadProcessHandle class.

BUG=None
TEST=Download tests still pass.


Review URL: http://codereview.chromium.org/6932046

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@84967 0039d316-1c4b-4281-b951-d872f2087c98

17 files changed, 211 insertions, 134 deletions

diff --git a/chrome/browser/download/download_file.cc b/chrome/browser/download/download_file.cc
index 629ee11..264bae3 100644
--- a/chrome/browser/download/download_file.cc
+++ b/chrome/browser/download/download_file.cc
@@ -21,11 +21,9 @@ DownloadFile::DownloadFile(const DownloadCreateInfo* info,
                info->received_bytes,
                info->save_info.file_stream),
       id_(info->download_id),
-      child_id_(info->child_id),
-      request_id_(info->request_id),
+      process_handle_(info->process_handle),
       download_manager_(download_manager) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
-
 }
 
 DownloadFile::~DownloadFile() {
@@ -34,12 +32,7 @@ DownloadFile::~DownloadFile() {
 
 void DownloadFile::CancelDownloadRequest(ResourceDispatcherHost* rdh) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
-  BrowserThread::PostTask(
-      BrowserThread::IO, FROM_HERE,
-      NewRunnableFunction(&download_util::CancelDownloadRequest,
-                          rdh,
-                          child_id_,
-                          request_id_));
+  download_util::CancelDownloadRequest(rdh, process_handle_);
 }
 
 DownloadManager* DownloadFile::GetDownloadManager() {
@@ -49,15 +42,15 @@ DownloadManager* DownloadFile::GetDownloadManager() {
 
 std::string DownloadFile::DebugString() const {
   return base::StringPrintf("{"
-                            " full_path_ = " "\"%s\""
                             " id_ = " "%d"
-                            " child_id_ = " "%d"
-                            " request_id_ = " "%d"
+                            " child_id = " "%d"
+                            " request_id = " "%d"
+                            " render_view_id = " "%d"
                             " Base File = %s"
                             " }",
-                            full_path_.value().c_str(),
                             id_,
-                            child_id_,
-                            request_id_,
+                            process_handle_.child_id(),
+                            process_handle_.request_id(),
+                            process_handle_.render_view_id(),
                             BaseFile::DebugString().c_str());
 }
diff --git a/chrome/browser/download/download_file.h b/chrome/browser/download/download_file.h
index 815f643..63060fe 100644
--- a/chrome/browser/download/download_file.h
+++ b/chrome/browser/download/download_file.h
@@ -11,6 +11,7 @@
 #include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
 #include "chrome/browser/download/base_file.h"
+#include "chrome/browser/download/download_process_handle.h"
 #include "chrome/browser/download/download_types.h"
 
 struct DownloadCreateInfo;
@@ -40,11 +41,9 @@ class DownloadFile : public BaseFile {
   // the DownloadFileManager for its internal record keeping.
   int id_;
 
-  // IDs for looking up the tab we are associated with.
-  int child_id_;
-
-  // Handle for informing the ResourceDispatcherHost of a UI based cancel.
-  int request_id_;
+  // The handle to the process information.  Used for operations outside the
+  // download system, specifically canceling a download.
+  DownloadProcessHandle process_handle_;
 
   // DownloadManager this download belongs to.
   scoped_refptr<DownloadManager> download_manager_;
diff --git a/chrome/browser/download/download_file_manager.cc b/chrome/browser/download/download_file_manager.cc
index 2522a98..faa85ba 100644
--- a/chrome/browser/download/download_file_manager.cc
+++ b/chrome/browser/download/download_file_manager.cc
@@ -11,6 +11,7 @@
 #include "base/utf_string_conversions.h"
 #include "build/build_config.h"
 #include "chrome/browser/download/download_manager.h"
+#include "chrome/browser/download/download_process_handle.h"
 #include "chrome/browser/download/download_util.h"
 #include "chrome/browser/history/download_create_info.h"
 #include "chrome/browser/net/chrome_url_request_context.h"
@@ -30,21 +31,6 @@ namespace {
 // cause it to become unresponsive (in milliseconds).
 const int kUpdatePeriodMs = 500;
 
-DownloadManager* DownloadManagerForRenderViewHost(int render_process_id,
-                                                  int render_view_id) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-
-  TabContents* contents = tab_util::GetTabContentsByID(render_process_id,
-                                                       render_view_id);
-  if (contents) {
-    Profile* profile = contents->profile();
-    if (profile)
-      return profile->GetDownloadManager();
-  }
-
-  return NULL;
-}
-
 }  // namespace
 
 DownloadFileManager::DownloadFileManager(ResourceDispatcherHost* rdh)
@@ -78,12 +64,8 @@ void DownloadFileManager::CreateDownloadFile(DownloadCreateInfo* info,
   scoped_ptr<DownloadFile>
       download_file(new DownloadFile(info, download_manager));
   if (!download_file->Initialize(get_hash)) {
-    BrowserThread::PostTask(
-        BrowserThread::IO, FROM_HERE,
-        NewRunnableFunction(&download_util::CancelDownloadRequest,
-                            resource_dispatcher_host_,
-                            info->child_id,
-                            info->request_id));
+    download_util::CancelDownloadRequest(resource_dispatcher_host_,
+                                         info->process_handle);
     delete info;
     return;
   }
@@ -97,7 +79,7 @@ void DownloadFileManager::CreateDownloadFile(DownloadCreateInfo* info,
   BrowserThread::PostTask(
       BrowserThread::IO, FROM_HERE,
       NewRunnableMethod(this, &DownloadFileManager::ResumeDownloadRequest,
-                        info->child_id, info->request_id));
+                        info->process_handle));
 
   StartUpdateTimer();
 
@@ -107,11 +89,14 @@ void DownloadFileManager::CreateDownloadFile(DownloadCreateInfo* info,
                         &DownloadManager::StartDownload, info));
 }
 
-void DownloadFileManager::ResumeDownloadRequest(int child_id, int request_id) {
+void DownloadFileManager::ResumeDownloadRequest(
+    DownloadProcessHandle process) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
 
   // This balances the pause in DownloadResourceHandler::OnResponseStarted.
-  resource_dispatcher_host_->PauseRequest(child_id, request_id, false);
+  resource_dispatcher_host_->PauseRequest(process.child_id(),
+                                          process.request_id(),
+                                          false);
 }
 
 DownloadFile* DownloadFileManager::GetDownloadFile(int id) {
@@ -158,15 +143,10 @@ void DownloadFileManager::StartDownload(DownloadCreateInfo* info) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   DCHECK(info);
 
-  DownloadManager* manager = DownloadManagerForRenderViewHost(
-      info->child_id, info->render_view_id);
+  DownloadManager* manager = info->process_handle.GetDownloadManager();
   if (!manager) {
-    BrowserThread::PostTask(
-        BrowserThread::IO, FROM_HERE,
-        NewRunnableFunction(&download_util::CancelDownloadRequest,
-                            resource_dispatcher_host_,
-                            info->child_id,
-                            info->request_id));
+    download_util::CancelDownloadRequest(resource_dispatcher_host_,
+                                         info->process_handle);
     delete info;
     return;
   }
@@ -178,7 +158,8 @@ void DownloadFileManager::StartDownload(DownloadCreateInfo* info) {
 
   BrowserThread::PostTask(BrowserThread::FILE, FROM_HERE,
       NewRunnableMethod(this, &DownloadFileManager::CreateDownloadFile,
-                        info, make_scoped_refptr(manager), hash_needed));
+                        info,
+                        make_scoped_refptr(manager), hash_needed));
 }
 
 // We don't forward an update to the UI thread here, since we want to throttle
diff --git a/chrome/browser/download/download_file_manager.h b/chrome/browser/download/download_file_manager.h
index 1d96b5d..6047aee 100644
--- a/chrome/browser/download/download_file_manager.h
+++ b/chrome/browser/download/download_file_manager.h
@@ -47,6 +47,7 @@
 #include "base/hash_tables.h"
 #include "base/memory/ref_counted.h"
 #include "base/timer.h"
+#include "chrome/browser/download/download_process_handle.h"
 #include "ui/gfx/native_widget_types.h"
 
 struct DownloadBuffer;
@@ -143,7 +144,9 @@ class DownloadFileManager
 
   // Tells the ResourceDispatcherHost to resume a download request
   // that was paused to wait for the on-disk file to be created.
-  void ResumeDownloadRequest(int child_id, int request_id);
+  // |process| is passed by value because this is called from other
+  // threads, and this way we don't have to worry about object lifetimes.
+  void ResumeDownloadRequest(DownloadProcessHandle process);
 
   // Called only on the download thread.
   DownloadFile* GetDownloadFile(int id);
diff --git a/chrome/browser/download/download_file_unittest.cc b/chrome/browser/download/download_file_unittest.cc
index 7826330..ab2758e 100644
--- a/chrome/browser/download/download_file_unittest.cc
+++ b/chrome/browser/download/download_file_unittest.cc
@@ -8,6 +8,7 @@
 #include "base/string_number_conversions.h"
 #include "chrome/browser/download/download_file.h"
 #include "chrome/browser/download/download_manager.h"
+#include "chrome/browser/download/download_process_handle.h"
 #include "chrome/browser/download/download_status_updater.h"
 #include "chrome/browser/download/download_util.h"
 #include "chrome/browser/download/mock_download_manager.h"
@@ -57,8 +58,8 @@ class DownloadFileTest : public testing::Test {
   virtual void CreateDownloadFile(scoped_ptr<DownloadFile>* file, int offset) {
     DownloadCreateInfo info;
     info.download_id = kDummyDownloadId + offset;
-    info.child_id = kDummyChildId;
-    info.request_id = kDummyRequestId - offset;
+    info.process_handle =
+        DownloadProcessHandle(kDummyChildId, -1, kDummyRequestId - offset);
     info.save_info.file_stream = file_stream_;
     file->reset(new DownloadFile(&info, download_manager_));
   }
diff --git a/chrome/browser/download/download_item.cc b/chrome/browser/download/download_item.cc
index c94d3b8..59126a8 100644
--- a/chrome/browser/download/download_item.cc
+++ b/chrome/browser/download/download_item.cc
@@ -135,8 +135,6 @@ DownloadItem::DownloadItem(DownloadManager* download_manager,
       danger_type_(NOT_DANGEROUS),
       auto_opened_(false),
       target_name_(info.original_name),
-      render_process_id_(-1),
-      request_id_(-1),
       save_as_(false),
       is_otr_(false),
       is_extension_install_(info.is_extension_install),
@@ -177,8 +175,7 @@ DownloadItem::DownloadItem(DownloadManager* download_manager,
                                  info.is_dangerous_url)),
       auto_opened_(false),
       target_name_(info.original_name),
-      render_process_id_(info.child_id),
-      request_id_(info.request_id),
+      process_handle_(info.process_handle),
       save_as_(info.prompt_user_for_save_location),
       is_otr_(is_otr),
       is_extension_install_(info.is_extension_install),
@@ -213,8 +210,6 @@ DownloadItem::DownloadItem(DownloadManager* download_manager,
       safety_state_(SAFE),
       danger_type_(NOT_DANGEROUS),
       auto_opened_(false),
-      render_process_id_(-1),
-      request_id_(-1),
       save_as_(false),
       is_otr_(is_otr),
       is_extension_install_(false),
@@ -616,28 +611,42 @@ std::string DownloadItem::DebugString(bool verbose) const {
   std::string description = base::StringPrintf(
       "{ id_ = %d state = %s", id_, DebugDownloadStateString(state()));
 
+  // Construct a string of the URL chain.
+  std::string url_list("<none>");
+  if (!url_chain_.empty()) {
+    std::vector<GURL>::const_iterator iter = url_chain_.begin();
+    std::vector<GURL>::const_iterator last = url_chain_.end();
+    url_list = (*iter).spec();
+    ++iter;
+    for ( ; verbose && (iter != last); ++iter) {
+      url_list += " -> ";
+      const GURL& next_url = *iter;
+      url_list += next_url.spec();
+    }
+  }
+
   if (verbose) {
     description += base::StringPrintf(
         " db_handle = %" PRId64
         " total_bytes = %" PRId64
-        " is_paused = %c"
-        " is_extension_install = %c"
-        " is_otr = %c"
-        " safety_state = %s"
-        " url = \"%s\""
+        " is_paused = " "%c"
+        " is_extension_install = " "%c"
+        " is_otr = " "%c"
+        " safety_state = " "%s"
+        " url_chain = " "\"%s\""
         " target_name_ = \"%" PRFilePath "\""
-        " full_path = \"%" PRFilePath "\" }",
+        " full_path = \"%" PRFilePath "\"",
         db_handle(),
         total_bytes(),
         is_paused() ? 'T' : 'F',
         is_extension_install() ? 'T' : 'F',
         is_otr() ? 'T' : 'F',
         DebugSafetyStateString(safety_state()),
-        url().spec().c_str(),
+        url_list.c_str(),
         target_name_.value().c_str(),
         full_path().value().c_str());
   } else {
-    description += " url = \"" + url().spec() + "\" }";
+    description += base::StringPrintf(" url = \"%s\"", url_list.c_str());
   }
   return description;
 }
diff --git a/chrome/browser/download/download_item.h b/chrome/browser/download/download_item.h
index aafab61..3a6bbd7 100644
--- a/chrome/browser/download/download_item.h
+++ b/chrome/browser/download/download_item.h
@@ -25,6 +25,7 @@
 #include "base/observer_list.h"
 #include "base/time.h"
 #include "base/timer.h"
+#include "chrome/browser/download/download_process_handle.h"
 #include "googleurl/src/gurl.h"
 
 class DownloadFileManager;
@@ -257,8 +258,6 @@ class DownloadItem {
   bool is_paused() const { return is_paused_; }
   bool open_when_complete() const { return open_when_complete_; }
   void set_open_when_complete(bool open) { open_when_complete_ = open; }
-  int render_process_id() const { return render_process_id_; }
-  int request_id() const { return request_id_; }
   SafetyState safety_state() const { return safety_state_; }
   void set_safety_state(SafetyState safety_state) {
     safety_state_ = safety_state;
@@ -273,6 +272,10 @@ class DownloadItem {
   void set_opened(bool opened) { opened_ = opened; }
   bool opened() const { return opened_; }
 
+  const DownloadProcessHandle& process_handle() const {
+    return process_handle_;
+  }
+
   // Returns the final target file path for the download.
   FilePath GetTargetFilePath() const;
 
@@ -382,9 +385,9 @@ class DownloadItem {
   // This stores their final target name.
   FilePath target_name_;
 
-  // For canceling or pausing requests.
-  int render_process_id_;
-  int request_id_;
+  // The handle to the process information.  Used for operations outside the
+  // download system.
+  DownloadProcessHandle process_handle_;
 
   // True if the item was downloaded as a result of 'save as...'
   bool save_as_;
diff --git a/chrome/browser/download/download_manager.cc b/chrome/browser/download/download_manager.cc
index fb80f8f..fb9fb7b 100644
--- a/chrome/browser/download/download_manager.cc
+++ b/chrome/browser/download/download_manager.cc
@@ -22,6 +22,7 @@
 #include "chrome/browser/download/download_history.h"
 #include "chrome/browser/download/download_item.h"
 #include "chrome/browser/download/download_prefs.h"
+#include "chrome/browser/download/download_process_handle.h"
 #include "chrome/browser/download/download_safe_browsing_client.h"
 #include "chrome/browser/download/download_status_updater.h"
 #include "chrome/browser/download/download_util.h"
@@ -429,8 +430,7 @@ void DownloadManager::OnPathExistenceAvailable(DownloadCreateInfo* info) {
     if (!select_file_dialog_.get())
       select_file_dialog_ = SelectFileDialog::Create(this);
 
-    TabContents* contents = tab_util::GetTabContentsByID(info->child_id,
-                                                         info->render_view_id);
+    TabContents* contents = info->process_handle.GetTabContents();
     SelectFileDialog::FileTypeInfo file_type_info;
     FilePath::StringType extension = info->suggested_path.Extension();
     if (!extension.empty()) {
@@ -702,22 +702,15 @@ void DownloadManager::DownloadCancelled(int32 download_id) {
     download_history_->UpdateEntry(download);
   }
 
-  DownloadCancelledInternal(download_id,
-                            download->render_process_id(),
-                            download->request_id());
+  DownloadCancelledInternal(download_id, download->process_handle());
 }
 
-void DownloadManager::DownloadCancelledInternal(int download_id,
-                                                int render_process_id,
-                                                int request_id) {
+void DownloadManager::DownloadCancelledInternal(
+    int download_id, DownloadProcessHandle process_handle) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   // Cancel the network request.  RDH is guaranteed to outlive the IO thread.
-  BrowserThread::PostTask(
-      BrowserThread::IO, FROM_HERE,
-      NewRunnableFunction(&download_util::CancelDownloadRequest,
-                          g_browser_process->resource_dispatcher_host(),
-                          render_process_id,
-                          request_id));
+  download_util::CancelDownloadRequest(
+      g_browser_process->resource_dispatcher_host(), process_handle);
 
   BrowserThread::PostTask(
       BrowserThread::FILE, FROM_HERE,
@@ -775,8 +768,7 @@ void DownloadManager::PauseDownload(int32 download_id, bool pause) {
       NewRunnableMethod(this,
                         &DownloadManager::PauseDownloadRequest,
                         g_browser_process->resource_dispatcher_host(),
-                        download->render_process_id(),
-                        download->request_id(),
+                        download->process_handle(),
                         pause));
 }
 
@@ -786,11 +778,12 @@ void DownloadManager::UpdateAppIcon() {
 }
 
 void DownloadManager::PauseDownloadRequest(ResourceDispatcherHost* rdh,
-                                           int render_process_id,
-                                           int request_id,
+                                           DownloadProcessHandle process_handle,
                                            bool pause) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
-  rdh->PauseRequest(render_process_id, request_id, pause);
+  rdh->PauseRequest(process_handle.child_id(),
+                    process_handle.request_id(),
+                    pause);
 }
 
 void DownloadManager::RemoveDownload(int64 download_handle) {
@@ -983,9 +976,7 @@ void DownloadManager::FileSelectionCanceled(void* params) {
   // The user didn't pick a place to save the file, so need to cancel the
   // download that's already in progress to the temporary location.
   DownloadCreateInfo* info = reinterpret_cast<DownloadCreateInfo*>(params);
-  DownloadCancelledInternal(info->download_id,
-                            info->child_id,
-                            info->request_id);
+  DownloadCancelledInternal(info->download_id, info->process_handle);
 }
 
 void DownloadManager::DangerousDownloadValidated(DownloadItem* download) {
@@ -1045,7 +1036,7 @@ void DownloadManager::OnCreateDownloadEntryComplete(
 
   // Show in the appropriate browser UI.
   // This includes buttons to save or cancel, for a dangerous download.
-  ShowDownloadInBrowser(info, download);
+  ShowDownloadInBrowser(&info.process_handle, download);
 
   // Inform interested objects about the new download.
   NotifyModelChanged();
@@ -1069,13 +1060,15 @@ void DownloadManager::OnCreateDownloadEntryComplete(
   }
 }
 
-void DownloadManager::ShowDownloadInBrowser(const DownloadCreateInfo& info,
-                                            DownloadItem* download) {
+void DownloadManager::ShowDownloadInBrowser(
+    DownloadProcessHandle* process_handle, DownloadItem* download) {
+  if (!process_handle)
+    return;
+
   // The 'contents' may no longer exist if the user closed the tab before we
   // get this start completion event. If it does, tell the origin TabContents
   // to display its download shelf.
-  TabContents* contents = tab_util::GetTabContentsByID(info.child_id,
-                                                       info.render_view_id);
+  TabContents* contents = process_handle->GetTabContents();
 
   // If the contents no longer exists, we start the download in the last active
   // browser. This is not ideal but better than fully hiding the download from
@@ -1086,8 +1079,10 @@ void DownloadManager::ShowDownloadInBrowser(const DownloadCreateInfo& info,
       contents = last_active->GetSelectedTabContents();
   }
 
-  if (contents)
-    contents->OnStartDownload(download);
+  if (!contents)
+    return;
+
+  contents->OnStartDownload(download);
 }
 
 // Clears the last download path, used to initialize "save as" dialogs.
diff --git a/chrome/browser/download/download_manager.h b/chrome/browser/download/download_manager.h
index f213a74..5cc4e0e 100644
--- a/chrome/browser/download/download_manager.h
+++ b/chrome/browser/download/download_manager.h
@@ -42,6 +42,7 @@
 #include "base/scoped_ptr.h"
 #include "base/time.h"
 #include "chrome/browser/download/download_status_updater_delegate.h"
+#include "chrome/browser/download/download_process_handle.h"
 #include "chrome/browser/ui/shell_dialogs.h"
 #include "content/browser/browser_thread.h"
 
@@ -194,7 +195,7 @@ class DownloadManager
       DownloadCreateInfo info, int64 db_handle);
 
   // Display a new download in the appropriate browser UI.
-  void ShowDownloadInBrowser(const DownloadCreateInfo& info,
+  void ShowDownloadInBrowser(DownloadProcessHandle* process_handle,
                              DownloadItem* download);
 
   // The number of in progress (including paused) downloads.
@@ -285,9 +286,10 @@ class DownloadManager
   void AttachDownloadItem(DownloadCreateInfo* info);
 
   // Download cancel helper function.
+  // |process_handle| is passed by value because it is ultimately passed to
+  // other threads, and this way we don't have to worry about object lifetimes.
   void DownloadCancelledInternal(int download_id,
-                                 int render_process_id,
-                                 int request_id);
+                                 DownloadProcessHandle process_handle);
 
   // All data has been downloaded.
   // |hash| is sha256 hash for the downloaded file. It is empty when the hash
@@ -302,9 +304,10 @@ class DownloadManager
 
   // Makes the ResourceDispatcherHost pause/un-pause a download request.
   // Called on the IO thread.
+  // |process_handle| is passed by value because this is called from other
+  // threads, and this way we don't have to worry about object lifetimes.
   void PauseDownloadRequest(ResourceDispatcherHost* rdh,
-                            int render_process_id,
-                            int request_id,
+                            DownloadProcessHandle process_handle,
                             bool pause);
 
   // Inform observers that the model has changed.
diff --git a/chrome/browser/download/download_process_handle.cc b/chrome/browser/download/download_process_handle.cc
new file mode 100644
index 0000000..f4c7f32
--- /dev/null
+++ b/chrome/browser/download/download_process_handle.cc
@@ -0,0 +1,39 @@
+// 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 "chrome/browser/profiles/profile.h"
+#include "chrome/browser/tab_contents/tab_util.h"
+#include "content/browser/browser_thread.h"
+#include "content/browser/tab_contents/tab_contents.h"
+
+DownloadProcessHandle::DownloadProcessHandle()
+    : child_id_(-1), render_view_id_(-1), request_id_(-1) {
+}
+
+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) {
+}
+
+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();
+}
diff --git a/chrome/browser/download/download_process_handle.h b/chrome/browser/download/download_process_handle.h
new file mode 100644
index 0000000..b722d61
--- /dev/null
+++ b/chrome/browser/download/download_process_handle.h
@@ -0,0 +1,42 @@
+// 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.
+
+#ifndef CHROME_BROWSER_DOWNLOAD_DOWNLOAD_PROCESS_HANDLE_H_
+#define CHROME_BROWSER_DOWNLOAD_DOWNLOAD_PROCESS_HANDLE_H_
+#pragma once
+
+class DownloadManager;
+class ResourceDispatcherHost;
+class TabContents;
+
+// A handle used by the download system for operations on external
+// objects associated with the download (e.g. URLRequest, TabContents,
+// DownloadManager).
+// This class needs to be copyable, so we can pass it across threads and not
+// worry about lifetime or const-ness.
+class DownloadProcessHandle {
+ public:
+  DownloadProcessHandle();
+  DownloadProcessHandle(int child_id, int render_view_id, int request_id);
+
+  // These functions must be called on the UI thread.
+  TabContents* GetTabContents();
+  DownloadManager* GetDownloadManager();
+
+  int child_id() const { return child_id_; }
+  int render_view_id() const { return render_view_id_; }
+  int request_id() const { return request_id_; }
+
+ private:
+  // The ID of the child process that started the download.
+  int child_id_;
+
+  // The ID of the render view that started the download.
+  int render_view_id_;
+
+  // The ID associated with the request used for the download.
+  int request_id_;
+};
+
+#endif  // CHROME_BROWSER_DOWNLOAD_DOWNLOAD_PROCESS_HANDLE_H_
diff --git a/chrome/browser/download/download_util.cc b/chrome/browser/download/download_util.cc
index 90fe73d..f68d676 100644
--- a/chrome/browser/download/download_util.cc
+++ b/chrome/browser/download/download_util.cc
@@ -809,13 +809,24 @@ void DownloadUrl(
                      *context);
 }
 
-void CancelDownloadRequest(ResourceDispatcherHost* rdh,
-                           int render_process_id,
-                           int request_id) {
+static void CancelDownloadRequestOnIOThread(
+    ResourceDispatcherHost* rdh, DownloadProcessHandle process_handle) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
   // |rdh| may be NULL in unit tests.
-  if (rdh)
-    rdh->CancelRequest(render_process_id, request_id, false);
+  if (!rdh)
+    return;
+
+  rdh->CancelRequest(process_handle.child_id(),
+                     process_handle.request_id(),
+                     false);
+}
+
+void CancelDownloadRequest(ResourceDispatcherHost* rdh,
+                           DownloadProcessHandle process_handle) {
+  BrowserThread::PostTask(
+      BrowserThread::IO, FROM_HERE,
+      NewRunnableFunction(&download_util::CancelDownloadRequestOnIOThread,
+                          rdh, process_handle));
 }
 
 void NotifyDownloadInitiated(int render_process_id, int render_view_id) {
diff --git a/chrome/browser/download/download_util.h b/chrome/browser/download/download_util.h
index d933d22..376fc18 100644
--- a/chrome/browser/download/download_util.h
+++ b/chrome/browser/download/download_util.h
@@ -13,6 +13,7 @@
 #include "base/basictypes.h"
 #include "base/file_path.h"
 #include "base/string16.h"
+#include "chrome/browser/download/download_process_handle.h"
 #include "ui/gfx/native_widget_types.h"
 
 #if defined(TOOLKIT_VIEWS)
@@ -242,9 +243,10 @@ void DownloadUrl(const GURL& url,
 
 // Tells the resource dispatcher host to cancel a download request.
 // Must be called on the IO thread.
+// |process_handle| is passed by value because it is ultimately passed to
+// other threads, and this way we don't have to worry about object lifetimes.
 void CancelDownloadRequest(ResourceDispatcherHost* rdh,
-                           int render_process_id,
-                           int request_id);
+                           DownloadProcessHandle process_handle);
 
 // Sends a notification on downloads being initiated
 // Must be called on the UI thread.
diff --git a/chrome/browser/history/download_create_info.cc b/chrome/browser/history/download_create_info.cc
index a7ece9a..12b23a8 100644
--- a/chrome/browser/history/download_create_info.cc
+++ b/chrome/browser/history/download_create_info.cc
@@ -26,9 +26,6 @@ DownloadCreateInfo::DownloadCreateInfo(const FilePath& path,
       state(state),
       download_id(download_id),
       has_user_gesture(has_user_gesture),
-      child_id(-1),
-      render_view_id(-1),
-      request_id(-1),
       db_handle(0),
       prompt_user_for_save_location(false),
       is_dangerous_file(false),
@@ -43,9 +40,6 @@ DownloadCreateInfo::DownloadCreateInfo()
       state(-1),
       download_id(-1),
       has_user_gesture(false),
-      child_id(-1),
-      render_view_id(-1),
-      request_id(-1),
       db_handle(0),
       prompt_user_for_save_location(false),
       is_dangerous_file(false),
@@ -62,24 +56,24 @@ bool DownloadCreateInfo::IsDangerous() {
 
 std::string DownloadCreateInfo::DebugString() const {
   return base::StringPrintf("{"
-                            " url_ = \"%s\""
+                            " download_id = %d"
+                            " url = \"%s\""
                             " path = \"%" PRFilePath "\""
                             " received_bytes = %" PRId64
                             " total_bytes = %" PRId64
                             " child_id = %d"
                             " render_view_id = %d"
                             " request_id = %d"
-                            " download_id = %d"
                             " prompt_user_for_save_location = %c"
                             " }",
+                            download_id,
                             url().spec().c_str(),
                             path.value().c_str(),
                             received_bytes,
                             total_bytes,
-                            child_id,
-                            render_view_id,
-                            request_id,
-                            download_id,
+                            process_handle.child_id(),
+                            process_handle.render_view_id(),
+                            process_handle.request_id(),
                             prompt_user_for_save_location ? 'T' : 'F');
 }
 
diff --git a/chrome/browser/history/download_create_info.h b/chrome/browser/history/download_create_info.h
index 361183e..77e966b 100644
--- a/chrome/browser/history/download_create_info.h
+++ b/chrome/browser/history/download_create_info.h
@@ -15,6 +15,7 @@
 #include "base/file_path.h"
 #include "base/time.h"
 #include "chrome/browser/download/download_file.h"
+#include "chrome/browser/download/download_process_handle.h"
 #include "googleurl/src/gurl.h"
 
 // Used for informing the download database of a new download, where we don't
@@ -57,9 +58,7 @@ struct DownloadCreateInfo {
   int32 state;
   int32 download_id;
   bool has_user_gesture;
-  int child_id;
-  int render_view_id;
-  int request_id;
+  DownloadProcessHandle process_handle;
   int64 db_handle;
   std::string content_disposition;
   std::string mime_type;
diff --git a/chrome/browser/renderer_host/download_resource_handler.cc b/chrome/browser/renderer_host/download_resource_handler.cc
index 7b7e02f..bbcab26 100644
--- a/chrome/browser/renderer_host/download_resource_handler.cc
+++ b/chrome/browser/renderer_host/download_resource_handler.cc
@@ -12,6 +12,7 @@
 #include "base/stringprintf.h"
 #include "chrome/browser/download/download_item.h"
 #include "chrome/browser/download/download_file_manager.h"
+#include "chrome/browser/download/download_process_handle.h"
 #include "chrome/browser/download/download_util.h"
 #include "chrome/browser/history/download_create_info.h"
 #include "content/browser/browser_thread.h"
@@ -88,9 +89,9 @@ bool DownloadResourceHandler::OnResponseStarted(int request_id,
   info->state = DownloadItem::IN_PROGRESS;
   info->download_id = download_id_;
   info->has_user_gesture = request_info->has_user_gesture();
-  info->child_id = global_id_.child_id;
-  info->render_view_id = render_view_id_;
-  info->request_id = global_id_.request_id;
+  info->process_handle = DownloadProcessHandle(global_id_.child_id,
+                                               render_view_id_,
+                                               global_id_.request_id);
   info->content_disposition = content_disposition_;
   info->mime_type = response->response_head.mime_type;
   // TODO(ahendrickson) -- Get the last modified time and etag, so we can
diff --git a/chrome/chrome_browser.gypi b/chrome/chrome_browser.gypi
index d0091a8..a17ec89 100644
--- a/chrome/chrome_browser.gypi
+++ b/chrome/chrome_browser.gypi
@@ -792,6 +792,8 @@
         'browser/download/download_manager.h',
         'browser/download/download_prefs.cc',
         'browser/download/download_prefs.h',
+        'browser/download/download_process_handle.cc',
+        'browser/download/download_process_handle.h',
         'browser/download/download_request_infobar_delegate.cc',
         'browser/download/download_request_infobar_delegate.h',
         'browser/download/download_request_limiter.cc',