Disable all the tests that are flaking more than 5% on Linux builders.

base/process/process_metrics_unittest.cc

Index: base/process/process_metrics_unittest.cc
diff --git a/base/process/process_metrics_unittest.cc b/base/process/process_metrics_unittest.cc
index 0bf8b9b0cf7c7c4e4b22548b5b5fa05b60e9111d..69f5e837cb98bd0986d431b2bbc44d2b4c4a7744 100644
--- a/base/process/process_metrics_unittest.cc
+++ b/base/process/process_metrics_unittest.cc
@@ -329,7 +329,8 @@ TEST(ProcessMetricsTest, ParseProcStatCPU) {
 // Disable on Android because base_unittests runs inside a Dalvik VM that
 // starts and stop threads (crbug.com/175563).
 #if defined(OS_LINUX)
-TEST(ProcessMetricsTest, GetNumberOfThreads) {
+// http://crbug.com/396455
+TEST(ProcessMetricsTest, DISABLED_GetNumberOfThreads) {
   const base::ProcessHandle current = base::GetCurrentProcessHandle();
   const int initial_threads = base::GetNumberOfThreads(current);
   ASSERT_GT(initial_threads, 0);