More aggressive IO asserts in content_browsertests.

Since browser test's main thread corresponds roughly to the product's UI
thread, it should behave in the same wrt base::ThreadRestrictions -
after this CL the body of browser tests derived from
content::ContentBrowserTest is not allowed to do file IO.

Motivation: The more aggressive IO asserts would have caught
https://crbug.com/626972 earlier.  Hopefully the more aggressive
asserting will also prevent future regressions in this area.

BUG=631145

Review-Url: https://codereview.chromium.org/2175933002
Cr-Commit-Position: refs/heads/master@{#408496}
diff --git a/PRESUBMIT.py b/PRESUBMIT.py
index 7d8c4a7..4521c6b 100644
--- a/PRESUBMIT.py
+++ b/PRESUBMIT.py
@@ -179,11 +179,18 @@
         r"^components[\\\/]crash[\\\/]app[\\\/]breakpad_mac\.mm$",
         r"^content[\\\/]shell[\\\/]browser[\\\/]layout_test[\\\/]" +
             r"test_info_extractor\.cc$",
+        r"^content[\\\/].*browser(|_)test[a-zA-Z_]*\.cc$",
         r"^content[\\\/]shell[\\\/]browser[\\\/]shell_browser_main\.cc$",
         r"^content[\\\/]shell[\\\/]browser[\\\/]shell_message_filter\.cc$",
+        r"^content[\\\/]test[\\\/]ppapi[\\\/]ppapi_test\.cc$",
         r"^mojo[\\\/]edk[\\\/]embedder[\\\/]" +
             r"simple_platform_shared_buffer_posix\.cc$",
         r"^net[\\\/]disk_cache[\\\/]cache_util\.cc$",
+        r"^net[\\\/]cert[\\\/]test_root_certs\.cc$",
+        r"^net[\\\/]test[\\\/]embedded_test_server[\\\/]" +
+            r"embedded_test_server\.cc$",
+        r"^net[\\\/]test[\\\/]spawned_test_server[\\\/]local_test_server\.cc$",
+        r"^net[\\\/]test[\\\/]test_data_directory\.cc$",
         r"^net[\\\/]url_request[\\\/]test_url_fetcher_factory\.cc$",
         r"^ui[\\\/]base[\\\/]material_design[\\\/]"
             "material_design_controller\.cc$",