Revert "Remove criticalsection.cc dependency on platform_thread.cc."

This reverts commit 5af97ee3ad.

Reason for revert: Breaks chrome compilation on Fuchsia, preventing rolls.

Sample failed bot run: https://ci.chromium.org/buildbot/tryserver.chromium.linux/fuchsia_arm64/59693


Sample compiler error:
In file included from ../../third_party/webrtc/rtc_base/platform_thread_types.cc:11:
../../third_party/webrtc/rtc_base/platform_thread_types.h:30:9: error: unknown type name 'pthread_t'
typedef pthread_t PlatformThreadRef;
        ^
../../third_party/webrtc/rtc_base/platform_thread_types.cc:47:10: error: use of undeclared identifier 'pthread_self'; did you mean 'zx_thread_self'?
  return pthread_self();
         ^~~~~~~~~~~~
         zx_thread_self
../../third_party/fuchsia-sdk/sysroot/aarch64-fuchsia/include/zircon/process.h:21:13: note: 'zx_thread_self' declared here
zx_handle_t zx_thread_self(void);
            ^
../../third_party/webrtc/rtc_base/platform_thread_types.cc:55:10: error: use of undeclared identifier 'pthread_equal'
  return pthread_equal(a, b);
         ^


Original change's description:
> Remove criticalsection.cc dependency on platform_thread.cc.
> 
> As part of this, I'm moving global thread related functions over to
> platform_thread_types.* and introducing platform_thread_types.cc
> for the implementation.
> 
> Change-Id: I4624877fb379e77d215f4ecd60f20b06d8df3ce5
> Bug: webrtc:8893
> Reviewed-on: https://webrtc-review.googlesource.com/53940
> Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
> Commit-Queue: Tommi <tommi@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#22037}

TBR=danilchap@webrtc.org,tommi@webrtc.org

Change-Id: I73cca942eedf804a0f3ed5a10f01135fbc6f275b
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: webrtc:8893
Reviewed-on: https://webrtc-review.googlesource.com/54340
Reviewed-by: Guido Urdaneta <guidou@webrtc.org>
Commit-Queue: Guido Urdaneta <guidou@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#22048}

rtc_base/BUILD.gn

@@ -217,7 +217,6 @@ rtc_source_set("rtc_base_approved_generic") {
     "platform_file.h",
     "platform_thread.cc",
     "platform_thread.h",
-    "platform_thread_types.cc",
     "platform_thread_types.h",
     "ptr_util.h",
     "race_checker.cc",

rtc_base/criticalsection.cc

@@ -11,7 +11,7 @@
 #include "rtc_base/criticalsection.h"
 
 #include "rtc_base/checks.h"
-#include "rtc_base/platform_thread_types.h"
+#include "rtc_base/platform_thread.h"
 
 // TODO(tommi): Split this file up to per-platform implementation files.
 

rtc_base/platform_thread.cc

@@ -25,6 +25,66 @@
 #endif
 
 namespace rtc {
+
+PlatformThreadId CurrentThreadId() {
+  PlatformThreadId ret;
+#if defined(WEBRTC_WIN)
+  ret = GetCurrentThreadId();
+#elif defined(WEBRTC_POSIX)
+#if defined(WEBRTC_MAC) || defined(WEBRTC_IOS)
+  ret = pthread_mach_thread_np(pthread_self());
+#elif defined(WEBRTC_ANDROID)
+  ret = gettid();
+#elif defined(WEBRTC_FUCHSIA)
+  ret = zx_thread_self();
+#elif defined(WEBRTC_LINUX)
+  ret = syscall(__NR_gettid);
+#else
+  // Default implementation for nacl and solaris.
+  ret = reinterpret_cast<pid_t>(pthread_self());
+#endif
+#endif  // defined(WEBRTC_POSIX)
+  RTC_DCHECK(ret);
+  return ret;
+}
+
+PlatformThreadRef CurrentThreadRef() {
+#if defined(WEBRTC_WIN)
+  return GetCurrentThreadId();
+#elif defined(WEBRTC_POSIX)
+  return pthread_self();
+#endif
+}
+
+bool IsThreadRefEqual(const PlatformThreadRef& a, const PlatformThreadRef& b) {
+#if defined(WEBRTC_WIN)
+  return a == b;
+#elif defined(WEBRTC_POSIX)
+  return pthread_equal(a, b);
+#endif
+}
+
+void SetCurrentThreadName(const char* name) {
+#if defined(WEBRTC_WIN)
+  struct {
+    DWORD dwType;
+    LPCSTR szName;
+    DWORD dwThreadID;
+    DWORD dwFlags;
+  } threadname_info = {0x1000, name, static_cast<DWORD>(-1), 0};
+
+  __try {
+    ::RaiseException(0x406D1388, 0, sizeof(threadname_info) / sizeof(DWORD),
+                     reinterpret_cast<ULONG_PTR*>(&threadname_info));
+  } __except (EXCEPTION_EXECUTE_HANDLER) {
+  }
+#elif defined(WEBRTC_LINUX) || defined(WEBRTC_ANDROID)
+  prctl(PR_SET_NAME, reinterpret_cast<unsigned long>(name));
+#elif defined(WEBRTC_MAC) || defined(WEBRTC_IOS)
+  pthread_setname_np(name);
+#endif
+}
+
 namespace {
 #if defined(WEBRTC_WIN)
 void CALLBACK RaiseFlag(ULONG_PTR param) {

rtc_base/platform_thread.h

@@ -20,6 +20,15 @@
 
 namespace rtc {
 
+PlatformThreadId CurrentThreadId();
+PlatformThreadRef CurrentThreadRef();
+
+// Compares two thread identifiers for equality.
+bool IsThreadRefEqual(const PlatformThreadRef& a, const PlatformThreadRef& b);
+
+// Sets the current thread name.
+void SetCurrentThreadName(const char* name);
+
 // Callback function that the spawned thread will enter once spawned.
 // A return value of false is interpreted as that the function has no
 // more work to do and that the thread can be released.

rtc_base/platform_thread_types.cc

@@ -1,80 +0,0 @@
-/*
- *  Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.
- *
- *  Use of this source code is governed by a BSD-style license
- *  that can be found in the LICENSE file in the root of the source
- *  tree. An additional intellectual property rights grant can be found
- *  in the file PATENTS.  All contributing project authors may
- *  be found in the AUTHORS file in the root of the source tree.
- */
-
-#include "rtc_base/platform_thread_types.h"
-
-#if defined(WEBRTC_LINUX)
-#include <sys/prctl.h>
-#include <sys/syscall.h>
-#endif
-
-#if defined(WEBRTC_FUCHSIA)
-#include <zircon/process.h>
-#endif
-
-namespace rtc {
-
-PlatformThreadId CurrentThreadId() {
-#if defined(WEBRTC_WIN)
-  return GetCurrentThreadId();
-#elif defined(WEBRTC_POSIX)
-#if defined(WEBRTC_MAC) || defined(WEBRTC_IOS)
-  return pthread_mach_thread_np(pthread_self());
-#elif defined(WEBRTC_ANDROID)
-  return gettid();
-#elif defined(WEBRTC_FUCHSIA)
-  return zx_thread_self();
-#elif defined(WEBRTC_LINUX)
-  return syscall(__NR_gettid);
-#else
-  // Default implementation for nacl and solaris.
-  return reinterpret_cast<pid_t>(pthread_self());
-#endif
-#endif  // defined(WEBRTC_POSIX)
-}
-
-PlatformThreadRef CurrentThreadRef() {
-#if defined(WEBRTC_WIN)
-  return GetCurrentThreadId();
-#elif defined(WEBRTC_POSIX)
-  return pthread_self();
-#endif
-}
-
-bool IsThreadRefEqual(const PlatformThreadRef& a, const PlatformThreadRef& b) {
-#if defined(WEBRTC_WIN)
-  return a == b;
-#elif defined(WEBRTC_POSIX)
-  return pthread_equal(a, b);
-#endif
-}
-
-void SetCurrentThreadName(const char* name) {
-#if defined(WEBRTC_WIN)
-  struct {
-    DWORD dwType;
-    LPCSTR szName;
-    DWORD dwThreadID;
-    DWORD dwFlags;
-  } threadname_info = {0x1000, name, static_cast<DWORD>(-1), 0};
-
-  __try {
-    ::RaiseException(0x406D1388, 0, sizeof(threadname_info) / sizeof(DWORD),
-                     reinterpret_cast<ULONG_PTR*>(&threadname_info));
-  } __except (EXCEPTION_EXECUTE_HANDLER) {  // NOLINT
-  }
-#elif defined(WEBRTC_LINUX) || defined(WEBRTC_ANDROID)
-  prctl(PR_SET_NAME, reinterpret_cast<unsigned long>(name));  // NOLINT
-#elif defined(WEBRTC_MAC) || defined(WEBRTC_IOS)
-  pthread_setname_np(name);
-#endif
-}
-
-}  // namespace rtc

rtc_base/platform_thread_types.h

@@ -32,21 +32,6 @@ typedef pthread_t PlatformThreadRef;
 typedef pid_t PlatformThreadId;
 typedef pthread_t PlatformThreadRef;
 #endif
-
-// Retrieve the ID of the current thread.
-PlatformThreadId CurrentThreadId();
-
-// Retrieves a reference to the current thread. On Windows, this is the same
-// as CurrentThreadId. On other platforms it's the pthread_t returned by
-// pthread_self().
-PlatformThreadRef CurrentThreadRef();
-
-// Compares two thread identifiers for equality.
-bool IsThreadRefEqual(const PlatformThreadRef& a, const PlatformThreadRef& b);
-
-// Sets the current thread name.
-void SetCurrentThreadName(const char* name);
-
 }  // namespace rtc
 
 #endif  // RTC_BASE_PLATFORM_THREAD_TYPES_H_