Active the delegate worker pool for chromium (3/3)

BUILD.gn

@@ -504,6 +504,9 @@ config("angle_backend_config") {
   if (angle_enable_null) {
     defines += [ "ANGLE_ENABLE_NULL" ]
   }
+  if (angle_delegate_workers) {
+    defines += [ "ANGLE_DELEGATE_WORKERS" ]
+  }
 
   configs = []
 

gni/angle.gni

@@ -91,6 +91,12 @@ declare_args() {
 }
 
 declare_args() {
+  # By default, ANGLE is using a thread pool for parallel compilation.
+  # Activating the delegate worker results in posting the tasks using the
+  # embedder API. In Chromium code base, it results in sending tasks to the
+  # worker thread pool.
+  angle_delegate_workers = build_with_chromium
+
   angle_enable_d3d9 = is_win && !angle_is_winuwp
   angle_enable_d3d11 = is_win
   angle_enable_gl =

include/platform/PlatformMethods.h

@@ -247,16 +247,11 @@ inline void DefaultCacheProgram(PlatformMethods *platform,
                                 const uint8_t *programBytes)
 {}
 
-using PostWorkerTaskCallback = void (*)(void *userData);
-using PostWorkerTaskFunc     = void (*)(PlatformMethods *platform,
+using PostWorkerTaskCallback                       = void (*)(void *userData);
+using PostWorkerTaskFunc                           = void (*)(PlatformMethods *platform,
                                     PostWorkerTaskCallback callback,
                                     void *userData);
-inline void DefaultPostWorkerTask(PlatformMethods *platform,
-                                  PostWorkerTaskCallback callback,
-                                  void *userData)
-{
-    callback(userData);
-}
+constexpr PostWorkerTaskFunc DefaultPostWorkerTask = nullptr;
 
 // Platform methods are enumerated here once.
 #define ANGLE_PLATFORM_OP(OP)                                    \
@@ -326,7 +321,6 @@ ANGLE_PLATFORM_EXPORT bool ANGLE_APIENTRY ANGLEGetDisplayPlatform(angle::EGLDisp
 // Sets the platform methods back to their defaults.
 // If display is not valid, behaviour is undefined.
 ANGLE_PLATFORM_EXPORT void ANGLE_APIENTRY ANGLEResetDisplayPlatform(angle::EGLDisplayType display);
-
 }  // extern "C"
 
 namespace angle

src/libANGLE/WorkerThread.cpp

@@ -12,13 +12,13 @@
 
 #include "libANGLE/trace.h"
 
-#if (ANGLE_STD_ASYNC_WORKERS == ANGLE_ENABLED)
+#if (ANGLE_DELEGATE_WORKERS == ANGLE_ENABLED) || (ANGLE_STD_ASYNC_WORKERS == ANGLE_ENABLED)
 #    include <condition_variable>
 #    include <future>
 #    include <mutex>
 #    include <queue>
 #    include <thread>
-#endif  // (ANGLE_STD_ASYNC_WORKERS == ANGLE_ENABLED)
+#endif  // (ANGLE_DELEGATE_WORKERS == ANGLE_ENABLED) || (ANGLE_STD_ASYNC_WORKERS == ANGLE_ENABLED)
 
 namespace angle
 {
@@ -320,11 +320,13 @@ std::shared_ptr<WorkerThreadPool> WorkerThreadPool::Create(bool multithreaded)
     std::shared_ptr<WorkerThreadPool> pool(nullptr);
 
 #if (ANGLE_DELEGATE_WORKERS == ANGLE_ENABLED)
-    if (multithreaded)
+    const bool hasPostWorkerTaskImpl = ANGLEPlatformCurrent()->postWorkerTask;
+    if (hasPostWorkerTaskImpl && multithreaded)
     {
         pool = std::shared_ptr<WorkerThreadPool>(new DelegateWorkerPool());
     }
-#elif (ANGLE_STD_ASYNC_WORKERS == ANGLE_ENABLED)
+#endif
+#if (!pool && ANGLE_STD_ASYNC_WORKERS == ANGLE_ENABLED)
     if (multithreaded)
     {
         pool = std::shared_ptr<WorkerThreadPool>(