Revert of Worker: Introduce per-global-scope task scheduler

third_party/WebKit/Source/core/dom/TaskRunnerHelper.cpp

Index: third_party/WebKit/Source/core/dom/TaskRunnerHelper.cpp
diff --git a/third_party/WebKit/Source/core/dom/TaskRunnerHelper.cpp b/third_party/WebKit/Source/core/dom/TaskRunnerHelper.cpp
index dc573a5973e0ff34a4ff4ca95b94235cd440c221..1a1cd884f8c88fa051d8d28d5eb2e60333289e23 100644
--- a/third_party/WebKit/Source/core/dom/TaskRunnerHelper.cpp
+++ b/third_party/WebKit/Source/core/dom/TaskRunnerHelper.cpp
@@ -7,8 +7,6 @@
 #include "core/dom/Document.h"
 #include "core/dom/ExecutionContext.h"
 #include "core/frame/LocalFrame.h"
-#include "core/workers/WorkerOrWorkletGlobalScope.h"
-#include "core/workers/WorkerThread.h"
 #include "platform/WebFrameScheduler.h"
 #include "platform/WebTaskRunner.h"
 #include "public/platform/Platform.h"
@@ -66,15 +64,10 @@
 
 RefPtr<WebTaskRunner> TaskRunnerHelper::Get(
     TaskType type,
-    ExecutionContext* executionContext) {
-  if (!executionContext)
-    return Get(type, ToDocument(executionContext));
-  if (executionContext->IsDocument())
-    return Get(type, ToDocument(executionContext));
-  if (executionContext->IsWorkerOrWorkletGlobalScope())
-    return Get(type, ToWorkerOrWorkletGlobalScope(executionContext));
-  executionContext = nullptr;
-  return Get(type, ToDocument(executionContext));
+    ExecutionContext* execution_context) {
+  return Get(type, execution_context && execution_context->IsDocument()
+                       ? static_cast<Document*>(execution_context)
+                       : nullptr);
 }
 
 RefPtr<WebTaskRunner> TaskRunnerHelper::Get(TaskType type,
@@ -83,49 +76,4 @@
              script_state ? ExecutionContext::From(script_state) : nullptr);
 }
 
-RefPtr<WebTaskRunner> TaskRunnerHelper::Get(
-    TaskType type,
-    WorkerOrWorkletGlobalScope* global_scope) {
-  DCHECK(global_scope);
-  // TODO(nhiroki): Add |DCHECK(global_scope->IsContextThread())| here after
-  // https://crbug.com/694925 is fixed.
-  return Get(type, global_scope->GetThread());
-}
-
-RefPtr<WebTaskRunner> TaskRunnerHelper::Get(TaskType type,
-                                            WorkerThread* worker_thread) {
-  switch (type) {
-    case TaskType::kDOMManipulation:
-    case TaskType::kUserInteraction:
-    case TaskType::kNetworking:
-    case TaskType::kHistoryTraversal:
-    case TaskType::kEmbed:
-    case TaskType::kMediaElementEvent:
-    case TaskType::kCanvasBlobSerialization:
-    case TaskType::kMicrotask:
-    case TaskType::kTimer:
-    case TaskType::kRemoteEvent:
-    case TaskType::kWebSocket:
-    case TaskType::kPostedMessage:
-    case TaskType::kUnshippedPortMessage:
-    case TaskType::kFileReading:
-    case TaskType::kDatabaseAccess:
-    case TaskType::kPresentation:
-    case TaskType::kSensor:
-    case TaskType::kPerformanceTimeline:
-    case TaskType::kWebGL:
-    case TaskType::kMiscPlatformAPI:
-    case TaskType::kUnspecedTimer:
-    case TaskType::kUnspecedLoading:
-    case TaskType::kUnthrottled:
-      // UnthrottledTaskRunner is generally discouraged in future.
-      // TODO(nhiroki): Identify which tasks can be throttled / suspendable and
-      // move them into other task runners. See also comments in
-      // Get(LocalFrame). (https://crbug.com/670534)
-      return worker_thread->GetGlobalScopeScheduler()->UnthrottledTaskRunner();
-  }
-  NOTREACHED();
-  return nullptr;
-}
-
 }  // namespace blink