Move platform_thread to base/threading and put in the base namespace. I left ...

chrome/browser/printing/printing_layout_uitest.cc

 // Copyright (c) 2010 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 "base/command_line.h"
 #include "base/file_util.h"
 #include "base/test/test_file_util.h"
 #include "base/threading/simple_thread.h"
 #include "chrome/test/automation/tab_proxy.h"
 #include "chrome/test/ui/ui_test.h"
@@ skipping 146 matching lines @@
               verification_name << "\"";
           prn_file = file;
           found_prn = true;
           file_util::Delete(file, false);
           continue;
         }
         EXPECT_TRUE(false);
       }
       if (found_emf && found_prn)
         break;
-      PlatformThread::Sleep(100);
+      base::PlatformThread::Sleep(100);
     }
     EXPECT_TRUE(found_emf) << ".PRN file is: " << prn_file;
     EXPECT_TRUE(found_prn) << ".EMF file is: " << emf_file;
     return emf_file;
   }
 
   static bool GenerateFiles() {
     return CommandLine::ForCurrentProcess()->HasSwitch(kGenerateSwitch);
   }
 
@@ skipping 71 matching lines @@
     for (;;) {
       // First enumerate the windows.
       dialog_window = FindDialogWindow(owner_process_);
 
       // Try to close it.
       if (dialog_window) {
         if (CloseDialogWindow(dialog_window)) {
           break;
         }
       }
-      PlatformThread::Sleep(10);
+      base::PlatformThread::Sleep(10);
     }
 
     // Now verify that it indeed closed itself.
     while (IsWindow(dialog_window)) {
       CloseDialogWindow(dialog_window);
-      PlatformThread::Sleep(10);
+      base::PlatformThread::Sleep(10);
     }
   }
 
   DWORD owner_process() { return owner_process_; }
 
  private:
   DWORD owner_process_;
 };
 
 }  // namespace
@@ skipping 138 matching lines @@
 
     // Force a navigation elsewhere to verify that it's fine with it.
     url = test_server.GetURL("files/printing/test1.html");
     EXPECT_EQ(AUTOMATION_MSG_NAVIGATION_SUCCESS,
               tab_proxy->NavigateToURL(url));
   }
   CloseBrowserAndServer();
 
   EXPECT_EQ(0., CompareWithResult(L"iframe")) << L"iframe";
 }