extensions/renderer/gc_callback.cc

   1 // Copyright 2015 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "extensions/renderer/gc_callback.h"
   6
   7 #include "base/bind.h"
   8 #include "base/message_loop/message_loop.h"
   9 #include "extensions/renderer/script_context.h"
  10
  11 namespace extensions {
  12
  13 GCCallback::GCCallback(ScriptContext* context,
  14                        const v8::Local<v8::Object>& object,
  15                        const v8::Local<v8::Function>& callback,
  16                        const base::Closure& fallback)
  17     : context_(context),
  18       object_(context->isolate(), object),
  19       callback_(context->isolate(), callback),
  20       fallback_(fallback),
  21       weak_ptr_factory_(this) {
  22   object_.SetWeak(this, OnObjectGC, v8::WeakCallbackType::kParameter);
  23   context->AddInvalidationObserver(base::Bind(&GCCallback::OnContextInvalidated,
  24                                               weak_ptr_factory_.GetWeakPtr()));
  25 }
  26
  27 GCCallback::~GCCallback() {}
  28
  29 // static
  30 void GCCallback::OnObjectGC(const v8::WeakCallbackInfo<GCCallback>& data) {
  31   // Usually FirstWeakCallback should do nothing other than reset |object_|
  32   // and then set a second weak callback to run later. We can sidestep that,
  33   // because posting a task to the current message loop is all but free - but
  34   // DO NOT add any more work to this method. The only acceptable place to add
  35   // code is RunCallback.
  36   GCCallback* self = data.GetParameter();
  37   self->object_.Reset();
  38   base::MessageLoop::current()->PostTask(
  39       FROM_HERE, base::Bind(&GCCallback::RunCallback,
  40                             self->weak_ptr_factory_.GetWeakPtr()));
  41 }
  42
  43 void GCCallback::RunCallback() {
  44   v8::Isolate* isolate = context_->isolate();
  45   v8::HandleScope handle_scope(isolate);
  46   context_->CallFunction(v8::Local<v8::Function>::New(isolate, callback_));
  47   delete this;
  48 }
  49
  50 void GCCallback::OnContextInvalidated() {
  51   fallback_.Run();
  52   delete this;
  53 }
  54
  55 }  // namespace extensions