[gin] Make a new IsolateHolder ctor for snapshot

gin/isolate_holder.cc

 // Copyright 2013 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 "gin/public/isolate_holder.h"
 
 #include <stddef.h>
 #include <stdlib.h>
 #include <string.h>
 
@@ skipping 50 matching lines @@
     size_t size;
     isolate_->GetCodeRange(&code_range, &size);
     Debug::CodeRangeCreatedCallback callback =
         DebugImpl::GetCodeRangeCreatedCallback();
     if (code_range && size && callback)
       callback(code_range, size);
   }
 #endif
 }
 
+IsolateHolder::IsolateHolder(intptr_t* reference_table,
+                             v8::StartupData* existing_blob)
+    : snapshot_creator_(
+          new v8::SnapshotCreator(reference_table, existing_blob)),
+      access_mode_(kSingleThread) {
+  v8::ArrayBuffer::Allocator* allocator = g_array_buffer_allocator;
+  CHECK(allocator) << "You need to invoke gin::IsolateHolder::Initialize first";
+  isolate_ = snapshot_creator_->GetIsolate();
+  isolate_data_.reset(
+      new PerIsolateData(isolate_, allocator, access_mode_, nullptr));
+  isolate_memory_dump_provider_.reset(new V8IsolateMemoryDumpProvider(this));
+#if defined(OS_WIN)
+  {
+    void* code_range;
+    size_t size;
+    isolate_->GetCodeRange(&code_range, &size);
+    Debug::CodeRangeCreatedCallback callback =
+        DebugImpl::GetCodeRangeCreatedCallback();
+    if (code_range && size && callback)
+      callback(code_range, size);
+  }
+#endif
+}
+
 IsolateHolder::~IsolateHolder() {
   if (task_observer_.get())
     base::MessageLoop::current()->RemoveTaskObserver(task_observer_.get());
 #if defined(OS_WIN)
   {
     void* code_range;
     size_t size;
     isolate_->GetCodeRange(&code_range, &size);
     Debug::CodeRangeDeletedCallback callback =
         DebugImpl::GetCodeRangeDeletedCallback();
@@ skipping 28 matching lines @@
   task_observer_.reset();
 }
 
 void IsolateHolder::EnableIdleTasks(
     std::unique_ptr<V8IdleTaskRunner> idle_task_runner) {
   DCHECK(isolate_data_.get());
   isolate_data_->EnableIdleTasks(std::move(idle_task_runner));
 }
 
 }  // namespace gin