Revert "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 bf7092f43637e145e103ecaf8a2fab58ac8aa82d..6cc8c97226775053cf02b99780793f8c9c4cf18b 100644
--- a/base/BUILD.gn
+++ b/base/BUILD.gn
@@ -280,10 +280,6 @@ 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",
@@ -1761,8 +1757,6 @@ 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",