More aggressive IO asserts in browser_tests.

chrome/test/base/in_process_browser_test.cc

Index: chrome/test/base/in_process_browser_test.cc
diff --git a/chrome/test/base/in_process_browser_test.cc b/chrome/test/base/in_process_browser_test.cc
index e277349d4ab37ad0707039713aee568d43c7fa1d..ba2c426d50a03d5a0272ad3ab1d1f73550b07de7 100644
--- a/chrome/test/base/in_process_browser_test.cc
+++ b/chrome/test/base/in_process_browser_test.cc
@@ -19,6 +19,7 @@
 #include "base/strings/string_number_conversions.h"
 #include "base/test/test_file_util.h"
 #include "base/threading/non_thread_safe.h"
+#include "base/threading/thread_restrictions.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "build/build_config.h"
 #include "chrome/browser/after_startup_task_utils.h"
@@ -540,8 +541,11 @@ void InProcessBrowserTest::RunTestOnMainThreadLoop() {
   autorelease_pool_->Recycle();
 #endif
 
-  if (!HasFatalFailure())
+  if (!HasFatalFailure()) {
+    bool old_io_allowed_value = base::ThreadRestrictions::SetIOAllowed(false);
     RunTestOnMainThread();
+    base::ThreadRestrictions::SetIOAllowed(old_io_allowed_value);
+  }
 #if defined(OS_MACOSX)
   autorelease_pool_->Recycle();
 #endif