Begin the first small step towards using FilePath everywhere:

chrome/browser/download/download_uitest.cc

 // Copyright (c) 2006-2008 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 <shlwapi.h>
 #include <sstream>
 #include <string>
 
 #include "base/command_line.h"
 #include "base/file_util.h"
@@ skipping 55 matching lines @@
 
 class DownloadTest : public UITest {
  protected:
   DownloadTest() : UITest() {}
 
   void CleanUpDownload(const std::wstring& client_filename,
                        const std::wstring& server_filename) {
     // Find the path on the client.
     std::wstring file_on_client(download_prefix_);
     file_on_client.append(client_filename);
-    EXPECT_PRED1(file_util::PathExists, file_on_client);
+    EXPECT_TRUE(file_util::PathExists(file_on_client));
 
     // Find the path on the server.
     std::wstring file_on_server;
     ASSERT_TRUE(PathService::Get(chrome::DIR_TEST_DATA,
                                  &file_on_server));
     file_on_server.append(L"\\");
     file_on_server.append(server_filename);
     ASSERT_TRUE(file_util::PathExists(file_on_server));
 
     // Check that we downloaded the file correctly.
-    EXPECT_PRED2(file_util::ContentsEqual, file_on_server, file_on_client);
+    EXPECT_TRUE(file_util::ContentsEqual(file_on_server,
+                                         file_on_client));
 
     // Check if the Zone Identifier is correclty set.
     if (VolumeSupportsADS(file_on_client))
       CheckZoneIdentifier(file_on_client);
 
     // Delete the client copy of the file.
-    EXPECT_PRED2(file_util::Delete, file_on_client, false);
+    EXPECT_TRUE(file_util::Delete(file_on_client, false));
   }
 
   void CleanUpDownload(const std::wstring& file) {
     CleanUpDownload(file, file);
   }
 
   virtual void SetUp() {
     UITest::SetUp();
     download_prefix_ = GetDownloadDirectory();
     download_prefix_ += file_util::kPathSeparator;
@@ skipping 19 matching lines @@
       EXPECT_EQ(2, GetTabCount());
       // TODO(tc): check download status text
 
       // Make sure the download shelf is showing.
       scoped_ptr<TabProxy> dl_tab(window->GetTab(0));
       ASSERT_TRUE(dl_tab.get());
       EXPECT_TRUE(WaitForDownloadShelfVisible(dl_tab.get()));
     }
 
     std::wstring filename = file_util::GetFilenameFromPath(url);
-    EXPECT_PRED1(file_util::PathExists, download_prefix_ + filename);
+    EXPECT_TRUE(file_util::PathExists(download_prefix_ + filename));
 
     // Delete the file we just downloaded.
     for (int i = 0; i < 10; ++i) {
       if (file_util::Delete(download_prefix_ + filename, false))
         break;
       Sleep(kWaitForActionMaxMsec / 10);
     }
     EXPECT_FALSE(file_util::PathExists(download_prefix_ + filename));
   }
 
@@ skipping 87 matching lines @@
   RunSizeTest(url, L"32.0 KB - " + filename, L"100% - " + filename);
 }
 
 // http://b/1158253
 TEST_F(DownloadTest, DISABLED_KnownSize) {
   std::wstring url(URLRequestSlowDownloadJob::kKnownSizeUrl);
   std::wstring filename = file_util::GetFilenameFromPath(url);
   RunSizeTest(url, L"71% - " + filename, L"100% - " + filename);
 }