[Bindings] Create and use V8 context snapshots

third_party/WebKit/Source/platform/bindings/ScriptWrappableVisitor.cpp

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "platform/bindings/ScriptWrappableVisitor.h"
 
 #include "platform/bindings/ActiveScriptWrappable.h"
 #include "platform/bindings/DOMWrapperWorld.h"
 #include "platform/bindings/ScopedPersistent.h"
 #include "platform/bindings/ScriptWrappable.h"
@@ skipping 76 matching lines @@
   }
 
   headers_to_unmark_.clear();
   marking_deque_.clear();
   verifier_deque_.clear();
   should_cleanup_ = false;
 }
 
 void ScriptWrappableVisitor::ScheduleIdleLazyCleanup() {
   // Some threads (e.g. PPAPI thread) don't have a scheduler.
-  if (!Platform::Current()->CurrentThread()->Scheduler())
+  WebThread* current_thread = Platform::Current()->CurrentThread();
+  if (!current_thread || !current_thread->Scheduler())

[Yuki, 2017/06/20 14:20:11]

Why current_thread can be null?

[peria, 2017/06/21 07:19:16]

ditto to V8Initializer.cpp

     return;
 
   if (idle_cleanup_task_scheduled_)
     return;
 
-  Platform::Current()->CurrentThread()->Scheduler()->PostIdleTask(
+  current_thread->Scheduler()->PostIdleTask(
       BLINK_FROM_HERE, WTF::Bind(&ScriptWrappableVisitor::PerformLazyCleanup,
                                  WTF::Unretained(this)));
   idle_cleanup_task_scheduled_ = true;
 }
 
 void ScriptWrappableVisitor::PerformLazyCleanup(double deadline_seconds) {
   idle_cleanup_task_scheduled_ = false;
 
   if (!should_cleanup_)
     return;
@@ skipping 187 matching lines @@
       V8PerIsolateData::From(isolate)->GetScriptWrappableVisitor();
   if (script_wrappable_visitor)
     script_wrappable_visitor->PerformCleanup();
 }
 
 WrapperVisitor* ScriptWrappableVisitor::CurrentVisitor(v8::Isolate* isolate) {
   return V8PerIsolateData::From(isolate)->GetScriptWrappableVisitor();
 }
 
 }  // namespace blink