Make MemoryCoordinator and WebThreadSupportingGC usable from a worker thread.

This is necessary to support nested workers.

Bug: 829119
Change-Id: Ib48d10fc724477f720e77a15237ab106d8ed86f9
Reviewed-on: https://chromium-review.googlesource.com/1012794Reviewed-by: Kenichi Ishibashi <bashi@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Commit-Queue: Nate Chapin <japhet@chromium.org>
Cr-Commit-Position: refs/heads/master@{#551389}

third_party/blink/renderer/platform/memory_coordinator.cc

@@ -57,18 +57,19 @@ void MemoryCoordinator::SetIsLowEndDeviceForTesting(bool is_low_end_device) {
 
 // static
 MemoryCoordinator& MemoryCoordinator::Instance() {
-  DEFINE_STATIC_LOCAL(Persistent<MemoryCoordinator>, external,
-                      (new MemoryCoordinator));
-  DCHECK(IsMainThread());
+  DEFINE_THREAD_SAFE_STATIC_LOCAL(CrossThreadPersistent<MemoryCoordinator>,
+                                  external, (new MemoryCoordinator));
   return *external.Get();
 }
 
 void MemoryCoordinator::RegisterThread(WebThread* thread) {
-  MemoryCoordinator::Instance().web_threads_.insert(thread);
+  MutexLocker lock(web_threads_mutex_);
+  web_threads_.insert(thread);
 }
 
 void MemoryCoordinator::UnregisterThread(WebThread* thread) {
-  MemoryCoordinator::Instance().web_threads_.erase(thread);
+  MutexLocker lock(web_threads_mutex_);
+  web_threads_.erase(thread);
 }
 
 MemoryCoordinator::MemoryCoordinator() = default;
@@ -110,6 +111,7 @@ void MemoryCoordinator::OnPurgeMemory() {
   WTF::Partitions::DecommitFreeableMemory();
 
   // Thread-specific data never issues a layout, so we are safe here.
+  MutexLocker lock(web_threads_mutex_);
   for (auto thread : web_threads_) {
     if (!thread->GetTaskRunner())
       continue;

third_party/blink/renderer/platform/memory_coordinator.h

@@ -11,6 +11,7 @@
 #include "third_party/blink/renderer/platform/heap/handle.h"
 #include "third_party/blink/renderer/platform/platform_export.h"
 #include "third_party/blink/renderer/platform/wtf/noncopyable.h"
+#include "third_party/blink/renderer/platform/wtf/threading_primitives.h"
 
 namespace blink {
 
@@ -51,8 +52,8 @@ class PLATFORM_EXPORT MemoryCoordinator final
   // the heap size.
   static void Initialize();
 
-  static void RegisterThread(WebThread*);
-  static void UnregisterThread(WebThread*);
+  void RegisterThread(WebThread*) LOCKS_EXCLUDED(web_threads_mutex_);
+  void UnregisterThread(WebThread*) LOCKS_EXCLUDED(web_threads_mutex_);
 
   void RegisterClient(MemoryCoordinatorClient*);
   void UnregisterClient(MemoryCoordinatorClient*);
@@ -81,6 +82,7 @@ class PLATFORM_EXPORT MemoryCoordinator final
 
   HeapHashSet<WeakMember<MemoryCoordinatorClient>> clients_;
   HashSet<WebThread*> web_threads_;
+  Mutex web_threads_mutex_;
 };
 
 }  // namespace blink

third_party/blink/renderer/platform/web_thread_supporting_gc.cc

@@ -28,7 +28,7 @@ WebThreadSupportingGC::WebThreadSupportingGC(
     const WebThreadCreationParams* params,
     WebThread* thread)
     : thread_(thread) {
-  DCHECK(IsMainThread());
+  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
   DCHECK(!params || !thread);
 #if DCHECK_IS_ON()
   // We call this regardless of whether an existing thread is given or not,
@@ -43,14 +43,14 @@ WebThreadSupportingGC::WebThreadSupportingGC(
         params ? *params : WebThreadCreationParams(WebThreadType::kTestThread));
     thread_ = owning_thread_.get();
   }
-  MemoryCoordinator::RegisterThread(thread_);
+  MemoryCoordinator::Instance().RegisterThread(thread_);
 }
 
 WebThreadSupportingGC::~WebThreadSupportingGC() {
-  DCHECK(IsMainThread());
+  DETACH_FROM_THREAD(thread_checker_);
   // WebThread's destructor blocks until all the tasks are processed.
   owning_thread_.reset();
-  MemoryCoordinator::UnregisterThread(thread_);
+  MemoryCoordinator::Instance().UnregisterThread(thread_);
 }
 
 void WebThreadSupportingGC::InitializeOnThread() {

third_party/blink/renderer/platform/web_thread_supporting_gc.h

@@ -6,6 +6,7 @@
 #define THIRD_PARTY_BLINK_RENDERER_PLATFORM_WEB_THREAD_SUPPORTING_GC_H_
 
 #include <memory>
+#include "base/threading/thread_checker.h"
 #include "third_party/blink/public/platform/platform.h"
 #include "third_party/blink/public/platform/web_thread.h"
 #include "third_party/blink/renderer/platform/heap/gc_task_runner.h"
@@ -86,6 +87,8 @@ class PLATFORM_EXPORT WebThreadSupportingGC final {
   // existing thread via createForThread().
   WebThread* thread_ = nullptr;
   std::unique_ptr<WebThread> owning_thread_;
+
+  THREAD_CHECKER(thread_checker_);
 };
 
 }  // namespace blink