Easier upload progress browser test for Mac buildbots

content/browser/loader/async_resource_handler_browsertest.cc

Index: content/browser/loader/async_resource_handler_browsertest.cc
diff --git a/content/browser/loader/async_resource_handler_browsertest.cc b/content/browser/loader/async_resource_handler_browsertest.cc
index cb48a2311158cfa2479b3b084fd9a1cfae0a5e2a..4276ce2b0aeffd6b93c18d8dacc6a339b4e459ae 100644
--- a/content/browser/loader/async_resource_handler_browsertest.cc
+++ b/content/browser/loader/async_resource_handler_browsertest.cc
@@ -28,8 +28,10 @@ const char kRedirectPostPath[] = "/redirect";
 
 // ThreadSanitizer is too slow to perform the full upload, so tests
 // using that build get an easier test which might not show two distinct
-// progress events. See crbug.com/526985.
-#if defined(THREAD_SANITIZER)
+// progress events. See crbug.com/526985. In addition, OSX buildbots have
+// experienced slowdowns on this test (crbug.com/548819), give them the easier
+// test too.
+#if defined(THREAD_SANITIZER) || defined(OS_MACOSX)
 const size_t kPayloadSize = 1062882;  // 2*3^12
 #else
 const size_t kPayloadSize = 28697814;  // 2*3^15