Track thread activities in order to diagnose hangs.

base/BUILD.gn

Index: base/BUILD.gn
diff --git a/base/BUILD.gn b/base/BUILD.gn
index 3063fa2ea657edd2efe96e74e7315454c282062c..f06cc22acd106a8cf918331788a7460492279aec 100644
--- a/base/BUILD.gn
+++ b/base/BUILD.gn
@@ -275,6 +275,10 @@ component("base") {
     # This file depends on files from the "debug/allocator" target,
     # but this target does not depend on "debug/allocator" (see
     # allocator.gyp for details).
+    "debug/activity_analyzer.cc",
+    "debug/activity_analyzer.h",
+    "debug/activity_tracker.cc",
+    "debug/activity_tracker.h",
     "debug/leak_annotations.h",
     "debug/leak_tracker.h",
     "debug/proc_maps_linux.cc",
@@ -1742,6 +1746,8 @@ test("base_unittests") {
     "containers/small_map_unittest.cc",
     "containers/stack_container_unittest.cc",
     "cpu_unittest.cc",
+    "debug/activity_analyzer_unittest.cc",
+    "debug/activity_tracker_unittest.cc",
     "debug/crash_logging_unittest.cc",
     "debug/debugger_unittest.cc",
     "debug/leak_tracker_unittest.cc",