diff --git a/logging/BUILD.gn b/logging/BUILD.gn
index 7b83c378cd..afee1946cd 100644
--- a/logging/BUILD.gn
+++ b/logging/BUILD.gn
@@ -219,7 +219,7 @@ rtc_static_library("rtc_event_log_impl_base") {
     ":rtc_event_log_impl_output",
     "../rtc_base:checks",
     "../rtc_base:rtc_base_approved",
-    "../rtc_base:rtc_task_queue_api",
+    "../rtc_base:rtc_task_queue",
     "../rtc_base:safe_minmax",
     "../rtc_base:sequenced_task_checker",
   ]
diff --git a/media/BUILD.gn b/media/BUILD.gn
index a9f8df8e37..90478a06be 100644
--- a/media/BUILD.gn
+++ b/media/BUILD.gn
@@ -69,7 +69,8 @@ rtc_static_library("rtc_media_base") {
   deps = [
     "../api:audio_options_api",
     "../rtc_base:checks",
-    "../rtc_base:rtc_task_queue_api",
+    "../rtc_base:rtc_base_approved",
+    "../rtc_base:rtc_task_queue",
     "../rtc_base:sanitizer",
     "../rtc_base:sequenced_task_checker",
     "../rtc_base:stringutils",
@@ -450,7 +451,7 @@ if (rtc_include_tests) {
       "../modules/video_coding:video_coding_utility",
       "../p2p:rtc_p2p",
       "../rtc_base:checks",
-      "../rtc_base:rtc_task_queue_api",
+      "../rtc_base:rtc_task_queue",
       "../rtc_base:stringutils",
     ]
     sources = [
@@ -552,7 +553,7 @@ if (rtc_include_tests) {
       "../pc:rtc_pc",
       "../pc:rtc_pc_base",
       "../rtc_base:checks",
-      "../rtc_base:rtc_task_queue_api",
+      "../rtc_base:rtc_task_queue",
       "../rtc_base:stringutils",
       "../test:field_trial",
     ]
diff --git a/pc/BUILD.gn b/pc/BUILD.gn
index 592f574eb8..4f69eef7c6 100644
--- a/pc/BUILD.gn
+++ b/pc/BUILD.gn
@@ -382,7 +382,7 @@ if (rtc_include_tests) {
       "../rtc_base:rtc_base",
       "../rtc_base:rtc_base_approved",
       "../rtc_base:rtc_base_tests_utils",
-      "../rtc_base:rtc_task_queue_api",
+      "../rtc_base:rtc_task_queue",
       "../test:test_support",
     ]
 
@@ -516,7 +516,7 @@ if (rtc_include_tests) {
       "../rtc_base:rtc_base_approved",
       "../rtc_base:rtc_base_tests_main",
       "../rtc_base:rtc_base_tests_utils",
-      "../rtc_base:rtc_task_queue_api",
+      "../rtc_base:rtc_task_queue",
       "../system_wrappers:metrics_default",
       "../system_wrappers:runtime_enabled_features_default",
       "../test:audio_codec_mocks",
diff --git a/rtc_base/BUILD.gn b/rtc_base/BUILD.gn
index 50e0b2499b..fbec98b485 100644
--- a/rtc_base/BUILD.gn
+++ b/rtc_base/BUILD.gn
@@ -23,7 +23,6 @@ group("base") {
     ":rtc_base",
     ":rtc_base_approved",
     ":rtc_task_queue",
-    ":sequenced_task_checker",
     ":weak_ptr",
   ]
   if (is_android) {
@@ -85,13 +84,169 @@ source_set("compile_assert_c") {
 rtc_source_set("rtc_base_approved") {
   visibility = [ "*" ]
   public_deps = [
+    ":atomicops",
+    ":criticalsection",
+    ":logging",
+    ":macromagic",
+    ":platform_thread",
+    ":platform_thread_types",
+    ":ptr_util",
+    ":refcount",
     ":rtc_base_approved_generic",
+    ":rtc_event",
+    ":safe_conversions",
+    ":stringutils",
+    ":thread_checker",
+    ":timeutils",
   ]
   if (is_mac && !build_with_chromium) {
     public_deps += [ ":rtc_base_approved_objc" ]
   }
 }
 
+rtc_source_set("macromagic") {
+  sources = [
+    "arraysize.h",
+    "basictypes.h",
+    "constructormagic.h",
+    "format_macros.h",
+    "stringize_macros.h",
+    "thread_annotations.h",
+  ]
+}
+
+rtc_source_set("platform_thread_types") {
+  sources = [
+    "platform_thread_types.cc",
+    "platform_thread_types.h",
+  ]
+}
+
+rtc_source_set("ptr_util") {
+  sources = [
+    "ptr_util.h",
+    "scoped_ref_ptr.h",
+  ]
+}
+
+rtc_source_set("refcount") {
+  sources = [
+    "refcount.h",
+    "refcountedobject.h",
+    "refcounter.h",
+  ]
+  deps = [
+    ":atomicops",
+    ":macromagic",
+  ]
+}
+
+rtc_source_set("criticalsection") {
+  sources = [
+    "criticalsection.cc",
+    "criticalsection.h",
+  ]
+  deps = [
+    ":atomicops",
+    ":checks",
+    ":macromagic",
+    ":platform_thread_types",
+    "..:typedefs",
+  ]
+}
+
+rtc_source_set("platform_thread") {
+  visibility = [
+    ":rtc_base_approved",
+    ":rtc_base_approved_generic",
+    ":rtc_task_queue_libevent",
+    ":rtc_task_queue_win",
+    ":sequenced_task_checker",
+  ]
+  sources = [
+    "platform_thread.cc",
+    "platform_thread.h",
+  ]
+  deps = [
+    ":atomicops",
+    ":checks",
+    ":macromagic",
+    ":platform_thread_types",
+    ":rtc_event",
+    ":thread_checker",
+    ":timeutils",
+    "..:typedefs",
+  ]
+}
+
+rtc_source_set("rtc_event") {
+  if (build_with_chromium) {
+    sources = [
+      "../../webrtc_overrides/rtc_base/event.cc",
+      "../../webrtc_overrides/rtc_base/event.h",
+    ]
+  } else {
+    sources = [
+      "event.cc",
+      "event.h",
+    ]
+  }
+
+  deps = [
+    ":checks",
+    ":macromagic",
+  ]
+}
+
+rtc_source_set("logging") {
+  deps = [
+    ":criticalsection",
+    ":macromagic",
+    ":platform_thread_types",
+    ":stringutils",
+    ":timeutils",
+  ]
+
+  if (build_with_chromium) {
+    # Dependency on chromium's logging (in //base).
+    deps += [ "//base:base" ]
+    sources = [
+      "../../webrtc_overrides/rtc_base/logging.cc",
+      "../../webrtc_overrides/rtc_base/logging.h",
+    ]
+  } else {
+    sources = [
+      "logging.cc",
+      "logging.h",
+    ]
+
+    # logging.h needs the deprecation header while downstream projects are
+    # removing code that depends on logging implementation details.
+    deps += [ ":deprecation" ]
+  }
+}
+
+rtc_source_set("thread_checker") {
+  sources = [
+    "thread_checker.h",
+    "thread_checker_impl.cc",
+    "thread_checker_impl.h",
+  ]
+  deps = [
+    ":checks",
+    ":criticalsection",
+    ":macromagic",
+    ":platform_thread_types",
+    "..:typedefs",
+  ]
+}
+
+rtc_source_set("atomicops") {
+  sources = [
+    "atomicops.h",
+  ]
+}
+
 rtc_source_set("checks") {
   sources = [
     "checks.cc",
@@ -140,8 +295,31 @@ rtc_source_set("safe_minmax") {
   ]
 }
 
+rtc_source_set("safe_conversions") {
+  sources = [
+    "numerics/safe_conversions.h",
+    "numerics/safe_conversions_impl.h",
+  ]
+  deps = [
+    ":checks",
+  ]
+}
+
+rtc_source_set("timeutils") {
+  sources = [
+    "timeutils.cc",
+    "timeutils.h",
+  ]
+  deps = [
+    ":checks",
+    ":safe_conversions",
+  ]
+}
+
 rtc_source_set("stringutils") {
   sources = [
+    "stringencode.cc",
+    "stringencode.h",
     "strings/string_builder.cc",
     "strings/string_builder.h",
     "stringutils.cc",
@@ -170,7 +348,6 @@ rtc_source_set("deprecation") {
 rtc_source_set("rtc_base_approved_generic") {
   visibility = [
     ":rtc_base_approved",
-    ":rtc_base_approved_objc",
     ":weak_ptr_unittests",
   ]
 
@@ -178,19 +355,29 @@ rtc_source_set("rtc_base_approved_generic") {
   defines = []
   libs = []
   deps = [
+    ":atomicops",
     ":checks",
+    ":criticalsection",
+    ":logging",
+    ":macromagic",
+    ":platform_thread",
+    ":platform_thread_types",
+    ":ptr_util",
+    ":refcount",
+    ":rtc_event",
+    ":rtc_task_queue",
     ":safe_compare",
+    ":safe_conversions",
     ":stringutils",
+    ":thread_checker",
+    ":timeutils",
     ":type_traits",
     "../:typedefs",
   ]
 
   sources = [
-    "arraysize.h",
-    "atomicops.h",
     "base64.cc",
     "base64.h",
-    "basictypes.h",
     "bind.h",
     "bitbuffer.cc",
     "bitbuffer.h",
@@ -202,18 +389,14 @@ rtc_source_set("rtc_base_approved_generic") {
     "bytebuffer.cc",
     "bytebuffer.h",
     "byteorder.h",
-    "constructormagic.h",
     "copyonwritebuffer.cc",
     "copyonwritebuffer.h",
-    "criticalsection.cc",
-    "criticalsection.h",
     "event_tracer.cc",
     "event_tracer.h",
     "file.cc",
     "file.h",
     "flags.cc",
     "flags.h",
-    "format_macros.h",
     "function_view.h",
     "ignore_wundef.h",
     "location.cc",
@@ -222,18 +405,11 @@ rtc_source_set("rtc_base_approved_generic") {
     "numerics/histogram_percentile_counter.h",
     "numerics/mod_ops.h",
     "numerics/moving_max_counter.h",
-    "numerics/safe_conversions.h",
-    "numerics/safe_conversions_impl.h",
     "onetimeevent.h",
     "pathutils.cc",
     "pathutils.h",
     "platform_file.cc",
     "platform_file.h",
-    "platform_thread.cc",
-    "platform_thread.h",
-    "platform_thread_types.cc",
-    "platform_thread_types.h",
-    "ptr_util.h",
     "race_checker.cc",
     "race_checker.h",
     "random.cc",
@@ -242,25 +418,12 @@ rtc_source_set("rtc_base_approved_generic") {
     "rate_statistics.h",
     "ratetracker.cc",
     "ratetracker.h",
-    "refcount.h",
-    "refcountedobject.h",
-    "refcounter.h",
-    "scoped_ref_ptr.h",
     "string_to_number.cc",
     "string_to_number.h",
-    "stringencode.cc",
-    "stringencode.h",
-    "stringize_macros.h",
     "swap_queue.h",
     "template_util.h",
-    "thread_annotations.h",
-    "thread_checker.h",
-    "thread_checker_impl.cc",
-    "thread_checker_impl.h",
     "timestampaligner.cc",
     "timestampaligner.h",
-    "timeutils.cc",
-    "timeutils.h",
     "trace_event.h",
     "zero_memory.cc",
     "zero_memory.h",
@@ -284,27 +447,6 @@ rtc_source_set("rtc_base_approved_generic") {
     sources += [ "file_win.cc" ]
   }
 
-  if (build_with_chromium) {
-    # Dependency on chromium's logging (in //base).
-    deps += [ "//base:base" ]
-    sources += [
-      "../../webrtc_overrides/rtc_base/event.cc",
-      "../../webrtc_overrides/rtc_base/event.h",
-      "../../webrtc_overrides/rtc_base/logging.cc",
-      "../../webrtc_overrides/rtc_base/logging.h",
-    ]
-  } else {
-    sources += [
-      "event.cc",
-      "event.h",
-      "logging.cc",
-      "logging.h",
-    ]
-
-    # logging.h needs the deprecation header while downstream projects are
-    # removing code that depends on logging implementation details.
-    deps += [ ":deprecation" ]
-  }
   if (is_component_build && is_win) {
     # Copy the VS runtime DLLs into the isolate so that they don't have to be
     # preinstalled on the target machine. The debug runtimes have a "d" at
@@ -395,16 +537,14 @@ if (is_mac && !build_with_chromium) {
       "logging_mac.mm",
     ]
     deps = [
-      ":rtc_base_approved_generic",
+      ":logging",
     ]
   }
 }
 
 rtc_source_set("rtc_task_queue") {
   visibility = [ "*" ]
-  deps = [
-    ":rtc_base_approved",
-  ]
+  deps = []
   public_deps = [
     ":rtc_task_queue_api",
   ]
@@ -421,47 +561,109 @@ rtc_source_set("rtc_task_queue") {
 # provided implementation should be used. An external implementation should
 # depend on rtc_task_queue_api.
 rtc_source_set("rtc_task_queue_api") {
+  # The visibility list is commented out so that we won't break external
+  # implementations, but left here to manually test as well as for sake of what
+  # targets we expect to depend on rtc_task_queue_api.
+  # visibility = [
+  #   ":rtc_task_queue",
+  #   ":rtc_task_queue_impl",
+  #   ":sequenced_task_checker",
+  # ]
   sources = [
     "task_queue.h",
   ]
   deps = [
-    ":rtc_base_approved",
+    ":macromagic",
+    ":ptr_util",
   ]
 }
 
-rtc_source_set("rtc_task_queue_impl") {
-  visibility = [ "*" ]
-  deps = [
-    ":checks",
-    ":rtc_base_approved",
-    ":rtc_task_queue_api",
-  ]
-  if (rtc_build_libevent) {
-    deps += [ "//base/third_party/libevent" ]
-  }
-  if (rtc_enable_libevent) {
+if (rtc_enable_libevent) {
+  rtc_source_set("rtc_task_queue_libevent") {
+    visibility = [ ":rtc_task_queue_impl" ]
     sources = [
       "task_queue_libevent.cc",
       "task_queue_posix.cc",
       "task_queue_posix.h",
     ]
+    deps = [
+      ":checks",
+      ":criticalsection",
+      ":logging",
+      ":platform_thread",
+      ":ptr_util",
+      ":refcount",
+      ":rtc_task_queue_api",
+      ":safe_conversions",
+      ":timeutils",
+    ]
+    if (rtc_build_libevent) {
+      deps += [ "//base/third_party/libevent" ]
+    }
+  }
+}
+
+if (is_mac || is_ios) {
+  rtc_source_set("rtc_task_queue_gcd") {
+    visibility = [ ":rtc_task_queue_impl" ]
+    sources = [
+      "task_queue_gcd.cc",
+      "task_queue_posix.cc",
+      "task_queue_posix.h",
+    ]
+    deps = [
+      ":checks",
+      ":logging",
+      ":ptr_util",
+      ":refcount",
+      ":rtc_task_queue_api",
+    ]
+  }
+}
+
+if (is_win) {
+  rtc_source_set("rtc_task_queue_win") {
+    visibility = [ ":rtc_task_queue_impl" ]
+    sources = [
+      "task_queue_win.cc",
+    ]
+    deps = [
+      ":checks",
+      ":criticalsection",
+      ":logging",
+      ":macromagic",
+      ":platform_thread",
+      ":ptr_util",
+      ":refcount",
+      ":rtc_event",
+      ":rtc_task_queue_api",
+      ":safe_conversions",
+      ":timeutils",
+    ]
+  }
+}
+
+rtc_source_set("rtc_task_queue_impl") {
+  visibility = [ "*" ]
+  if (rtc_enable_libevent) {
+    deps = [
+      ":rtc_task_queue_libevent",
+    ]
   } else {
     if (is_mac || is_ios) {
-      sources = [
-        "task_queue_gcd.cc",
-        "task_queue_posix.cc",
-        "task_queue_posix.h",
+      deps = [
+        ":rtc_task_queue_gcd",
       ]
     }
     if (is_win) {
-      sources = [
-        "task_queue_win.cc",
+      deps = [
+        ":rtc_task_queue_win",
       ]
     }
   }
 }
 
-rtc_static_library("sequenced_task_checker") {
+rtc_source_set("sequenced_task_checker") {
   sources = [
     "sequenced_task_checker.h",
     "sequenced_task_checker_impl.cc",
@@ -469,8 +671,10 @@ rtc_static_library("sequenced_task_checker") {
   ]
   deps = [
     ":checks",
-    ":rtc_base_approved",
+    ":criticalsection",
+    ":macromagic",
     ":rtc_task_queue",
+    ":thread_checker",
   ]
 }
 
@@ -480,7 +684,8 @@ rtc_static_library("weak_ptr") {
     "weak_ptr.h",
   ]
   deps = [
-    ":rtc_base_approved",
+    ":ptr_util",
+    ":refcount",
     ":sequenced_task_checker",
   ]
 }
@@ -869,7 +1074,6 @@ rtc_source_set("rtc_base_tests_utils") {
     "nattypes.h",
     "proxyserver.cc",
     "proxyserver.h",
-    "refcount.h",
     "sigslottester.h",
     "sigslottester.h.pump",
     "testbase64.h",
@@ -1070,6 +1274,7 @@ if (rtc_include_tests) {
       ":rtc_base_approved_generic",
       ":rtc_base_tests_main",
       ":rtc_base_tests_utils",
+      ":rtc_event",
       ":rtc_task_queue",
       ":weak_ptr",
       "../test:test_support",
diff --git a/rtc_base/criticalsection.cc b/rtc_base/criticalsection.cc
index f9168d89e8..b2bbd03e02 100644
--- a/rtc_base/criticalsection.cc
+++ b/rtc_base/criticalsection.cc
@@ -10,6 +10,7 @@
 
 #include "rtc_base/criticalsection.h"
 
+#include "rtc_base/atomicops.h"
 #include "rtc_base/checks.h"
 #include "rtc_base/platform_thread_types.h"
 
diff --git a/rtc_base/criticalsection.h b/rtc_base/criticalsection.h
index 1ef9634efe..569e1479bd 100644
--- a/rtc_base/criticalsection.h
+++ b/rtc_base/criticalsection.h
@@ -11,7 +11,6 @@
 #ifndef RTC_BASE_CRITICALSECTION_H_
 #define RTC_BASE_CRITICALSECTION_H_
 
-#include "rtc_base/atomicops.h"
 #include "rtc_base/checks.h"
 #include "rtc_base/constructormagic.h"
 #include "rtc_base/platform_thread_types.h"
diff --git a/rtc_base/criticalsection_unittest.cc b/rtc_base/criticalsection_unittest.cc
index f5d6957fcf..6792504353 100644
--- a/rtc_base/criticalsection_unittest.cc
+++ b/rtc_base/criticalsection_unittest.cc
@@ -13,6 +13,7 @@
 #include <vector>
 
 #include "rtc_base/arraysize.h"
+#include "rtc_base/atomicops.h"
 #include "rtc_base/checks.h"
 #include "rtc_base/criticalsection.h"
 #include "rtc_base/event.h"
diff --git a/rtc_base/event_tracer.cc b/rtc_base/event_tracer.cc
index 9cbda972e3..3461ec625a 100644
--- a/rtc_base/event_tracer.cc
+++ b/rtc_base/event_tracer.cc
@@ -14,6 +14,7 @@
 #include <string>
 #include <vector>
 
+#include "rtc_base/atomicops.h"
 #include "rtc_base/checks.h"
 #include "rtc_base/criticalsection.h"
 #include "rtc_base/event.h"
diff --git a/rtc_base/format_macros.h b/rtc_base/format_macros.h
index d252a94cca..48127e16e0 100644
--- a/rtc_base/format_macros.h
+++ b/rtc_base/format_macros.h
@@ -24,8 +24,6 @@
 //   printf("xyz: %" PRIuS, size);
 // The "u" in the macro corresponds to %u, and S is for "size".
 
-#include "typedefs.h"  // NOLINT(build/include)
-
 #if defined(WEBRTC_POSIX)
 
 #if (defined(_INTTYPES_H) || defined(_INTTYPES_H_)) && !defined(PRId64)
diff --git a/rtc_base/platform_thread.cc b/rtc_base/platform_thread.cc
index ca2ce1367b..79d9d53aee 100644
--- a/rtc_base/platform_thread.cc
+++ b/rtc_base/platform_thread.cc
@@ -13,7 +13,6 @@
 #include "rtc_base/atomicops.h"
 #include "rtc_base/checks.h"
 #include "rtc_base/timeutils.h"
-#include "rtc_base/trace_event.h"
 
 #if defined(WEBRTC_LINUX)
 #include <sys/prctl.h>
@@ -178,8 +177,6 @@ void PlatformThread::Run() {
 #endif
 
   do {
-    TRACE_EVENT1("webrtc", "PlatformThread::Run", "name", name_.c_str());
-
     // The interface contract of Start/Stop is that for a successful call to
     // Start, there should be at least one call to the run function.  So we
     // call the function before checking |stop_|.
diff --git a/rtc_base/sequenced_task_checker_impl.cc b/rtc_base/sequenced_task_checker_impl.cc
index d7f46ead7d..16069c25f7 100644
--- a/rtc_base/sequenced_task_checker_impl.cc
+++ b/rtc_base/sequenced_task_checker_impl.cc
@@ -14,7 +14,6 @@
 #include <dispatch/dispatch.h>
 #endif
 
-#include "rtc_base/platform_thread.h"
 #include "rtc_base/sequenced_task_checker.h"
 #include "rtc_base/task_queue.h"
 
diff --git a/rtc_base/sequenced_task_checker_impl.h b/rtc_base/sequenced_task_checker_impl.h
index 86d5ef0213..293b1ac297 100644
--- a/rtc_base/sequenced_task_checker_impl.h
+++ b/rtc_base/sequenced_task_checker_impl.h
@@ -11,6 +11,7 @@
 #ifndef RTC_BASE_SEQUENCED_TASK_CHECKER_IMPL_H_
 #define RTC_BASE_SEQUENCED_TASK_CHECKER_IMPL_H_
 
+#include "rtc_base/criticalsection.h"
 #include "rtc_base/thread_checker.h"
 
 namespace rtc {
diff --git a/rtc_base/thread_checker_impl.cc b/rtc_base/thread_checker_impl.cc
index 6ec5c91d2e..850f2ac3cf 100644
--- a/rtc_base/thread_checker_impl.cc
+++ b/rtc_base/thread_checker_impl.cc
@@ -12,8 +12,6 @@
 
 #include "rtc_base/thread_checker_impl.h"
 
-#include "rtc_base/platform_thread.h"
-
 namespace rtc {
 
 ThreadCheckerImpl::ThreadCheckerImpl() : valid_thread_(CurrentThreadRef()) {