Switch MessagePumpForIO to use completion ports on Windows....

net/disk_cache/mapped_file_unittest.cc

Index: net/disk_cache/mapped_file_unittest.cc
===================================================================
--- net/disk_cache/mapped_file_unittest.cc	(revision 4870)
+++ net/disk_cache/mapped_file_unittest.cc	(working copy)
@@ -95,6 +95,8 @@
   g_cache_tests_max_id = 0;
   g_cache_tests_received = 0;
 
+  MessageLoopHelper helper;
+
   char buffer1[20];
   char buffer2[20];
   CacheTestFillBuffer(buffer1, sizeof(buffer1), false);
@@ -105,14 +107,14 @@
   int expected = completed ? 0 : 1;
 
   g_cache_tests_max_id = 1;
-  WaitForCallbacks(expected);
+  helper.WaitUntilCacheIoFinished(expected);
 
   EXPECT_TRUE(file->Read(buffer2, sizeof(buffer2), 1024 * 1024, &callback,
               &completed));
   if (!completed)
     expected++;
 
-  WaitForCallbacks(expected);
+  helper.WaitUntilCacheIoFinished(expected);
 
   EXPECT_EQ(expected, g_cache_tests_received);
   EXPECT_FALSE(g_cache_tests_error);