Make DownloadItem derive SupportsUserData instead of re-implementing it.

chrome/browser/chromeos/gdata/gdata_download_observer.cc

Index: chrome/browser/chromeos/gdata/gdata_download_observer.cc
diff --git a/chrome/browser/chromeos/gdata/gdata_download_observer.cc b/chrome/browser/chromeos/gdata/gdata_download_observer.cc
index c6299d07349e4096619fb44ecbaf8a7108beb8e9..ee2cbf3899ef426a9007da22a209218227043095 100644
--- a/chrome/browser/chromeos/gdata/gdata_download_observer.cc
+++ b/chrome/browser/chromeos/gdata/gdata_download_observer.cc
@@ -6,6 +6,7 @@
 
 #include "base/callback.h"
 #include "base/file_util.h"
+#include "base/supports_user_data.h"
 #include "chrome/browser/chromeos/gdata/gdata.pb.h"
 #include "chrome/browser/chromeos/gdata/gdata_documents_service.h"
 #include "chrome/browser/chromeos/gdata/gdata_file_system_interface.h"
@@ -58,7 +59,7 @@ class UploadingExternalData : public DownloadCompletionBlocker {
 };
 
 // External Data stored in DownloadItem for gdata path.
-class GDataExternalData : public DownloadItem::ExternalData {
+class GDataExternalData : public base::SupportsUserData::Data {
  public:
   explicit GDataExternalData(const FilePath& path) : file_path_(path) {}
   virtual ~GDataExternalData() {}
@@ -72,13 +73,13 @@ class GDataExternalData : public DownloadItem::ExternalData {
 // Extracts UploadingExternalData* from |download|.
 UploadingExternalData* GetUploadingExternalData(DownloadItem* download) {
   return static_cast<UploadingExternalData*>(
-      download->GetExternalData(&kUploadingKey));
+      download->GetUserData(&kUploadingKey));
 }
 
 // Extracts GDataExternalData* from |download|.
 GDataExternalData* GetGDataExternalData(DownloadItem* download) {
   return static_cast<GDataExternalData*>(
-      download->GetExternalData(&kGDataPathKey));
+      download->GetUserData(&kGDataPathKey));
 }
 
 void RunSubstituteGDataDownloadCallback(
@@ -233,15 +234,15 @@ void GDataDownloadObserver::SetDownloadParams(const FilePath& gdata_path,
     return;
 
   if (gdata::util::IsUnderGDataMountPoint(gdata_path)) {
-    download->SetExternalData(&kGDataPathKey,
-                              new GDataExternalData(gdata_path));
+    download->SetUserData(&kGDataPathKey,
+                          new GDataExternalData(gdata_path));
     download->SetDisplayName(gdata_path.BaseName());
     download->SetIsTemporary(true);
   } else if (IsGDataDownload(download)) {
     // This may have been previously set if the default download folder is
     // /drive, and the user has now changed the download target to a local
     // folder.
-    download->SetExternalData(&kGDataPathKey, NULL);
+    download->SetUserData(&kGDataPathKey, NULL);
     download->SetDisplayName(gdata_path);
     // TODO(achuith): This is not quite right.
     download->SetIsTemporary(false);
@@ -400,8 +401,8 @@ void GDataDownloadObserver::RemovePendingDownload(DownloadItem* download) {
 }
 
 void GDataDownloadObserver::DetachFromDownload(DownloadItem* download) {
-  download->SetExternalData(&kUploadingKey, NULL);
-  download->SetExternalData(&kGDataPathKey, NULL);
+  download->SetUserData(&kUploadingKey, NULL);
+  download->SetUserData(&kGDataPathKey, NULL);
   download->RemoveObserver(this);
 }
 
@@ -413,7 +414,7 @@ void GDataDownloadObserver::UploadDownloadItem(DownloadItem* download) {
     return;
 
   // Initialize uploading external data.
-  download->SetExternalData(&kUploadingKey,
+  download->SetUserData(&kUploadingKey,
                             new UploadingExternalData(gdata_uploader_));
 
   // Create UploadFileInfo structure for the download item.