Switch content tests to use BrowserThreadImpl directly.

content/browser/download/download_file_unittest.cc

Index: content/browser/download/download_file_unittest.cc
diff --git a/content/browser/download/download_file_unittest.cc b/content/browser/download/download_file_unittest.cc
index 4d42171d26425443d58a40692bab57049eab0aac..e91eabb2e4e5e7dd5300d7c1e42c3d743d5ec417 100644
--- a/content/browser/download/download_file_unittest.cc
+++ b/content/browser/download/download_file_unittest.cc
@@ -5,6 +5,7 @@
 #include "base/file_util.h"
 #include "base/message_loop.h"
 #include "base/string_number_conversions.h"
+#include "content/browser/browser_thread_impl.h"
 #include "content/browser/download/download_create_info.h"
 #include "content/browser/download/download_file.h"
 #include "content/browser/download/download_id.h"
@@ -14,11 +15,12 @@
 #include "content/browser/download/download_status_updater.h"
 #include "content/browser/download/mock_download_manager.h"
 #include "content/browser/download/mock_download_manager_delegate.h"
-#include "content/test/test_browser_thread.h"
 #include "net/base/file_stream.h"
 #include "net/base/net_errors.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
+using content::BrowserThreadImpl;
+
 DownloadId::Domain kValidIdDomain = "valid DownloadId::Domain";
 
 class DownloadFileTest : public testing::Test {
@@ -113,9 +115,9 @@ class DownloadFileTest : public testing::Test {
   MessageLoop loop_;
   scoped_refptr<DownloadIdFactory> id_factory_;
   // UI thread.
-  content::TestBrowserThread ui_thread_;
+  BrowserThreadImpl ui_thread_;
   // File thread to satisfy debug checks in DownloadFile.
-  content::TestBrowserThread file_thread_;
+  BrowserThreadImpl file_thread_;
 
   // Keep track of what data should be saved to the disk file.
   std::string expected_data_;