DownloadManager intereface refactoring to allow cleaner DownloadItem unit tests.

chrome/browser/download/download_prefs.cc

Index: chrome/browser/download/download_prefs.cc
diff --git a/chrome/browser/download/download_prefs.cc b/chrome/browser/download/download_prefs.cc
index feced8d092b91f6d9f62d61d794239569949db79..cc5fe64be4ba28ead5e99fd4f12186ef7224aaf2 100644
--- a/chrome/browser/download/download_prefs.cc
+++ b/chrome/browser/download/download_prefs.cc
@@ -14,12 +14,15 @@
 #include "base/utf_string_conversions.h"
 #include "chrome/browser/download/chrome_download_manager_delegate.h"
 #include "chrome/browser/download/download_extensions.h"
+#include "chrome/browser/download/download_service.h"
 #include "chrome/browser/download/download_util.h"
 #include "chrome/browser/prefs/pref_service.h"
+#include "chrome/browser/profiles/profile.h"
 #include "chrome/common/pref_names.h"
 #include "content/browser/download/download_manager.h"
 #include "content/browser/download/save_package.h"
 #include "content/public/browser/browser_thread.h"
+#include "chrome/browser/download/download_service_factory.h"
 
 using content::BrowserThread;
 
@@ -102,6 +105,15 @@ DownloadPrefs* DownloadPrefs::FromDownloadManager(
   return delegate->download_prefs();
 }
 
+// static
+DownloadPrefs* DownloadPrefs::FromBrowserContext(
+    content::BrowserContext* browser_context) {
+  Profile* profile = static_cast<Profile*>(browser_context);
+  DownloadService* download_service =
+      DownloadServiceFactory::GetForProfile(profile);
+  return FromDownloadManager(download_service->GetDownloadManager());
+}
+
 bool DownloadPrefs::PromptForDownload() const {
   // If the DownloadDirectory policy is set, then |prompt_for_download_| should
   // always be false.