Reject outstanding promises asynchronously when cleared

media/base/cdm_promise_adapter.cc

 // Copyright 2014 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 "media/base/cdm_promise_adapter.h"
 
 #include <utility>
 
+#include "base/bind.h"
+#include "base/location.h"
+#include "base/single_thread_task_runner.h"
+#include "base/thread_task_runner_handle.h"
 #include "media/base/media_keys.h"
 
 namespace media {
 
+static void AbortPromise(scoped_ptr<CdmPromise> promise) {
+  promise->reject(MediaKeys::UNKNOWN_ERROR, 0, "Operation aborted.");
+}
+
 CdmPromiseAdapter::CdmPromiseAdapter() : next_promise_id_(1) {
 }
 
 CdmPromiseAdapter::~CdmPromiseAdapter() {
   DCHECK(promises_.empty());
   DCHECK(thread_checker_.CalledOnValidThread());
   Clear();
 }
 
 uint32_t CdmPromiseAdapter::SavePromise(scoped_ptr<CdmPromise> promise) {
@@ skipping 30 matching lines @@
   scoped_ptr<CdmPromise> promise = TakePromise(promise_id);
   if (!promise) {
     NOTREACHED() << "No promise found for promise_id " << promise_id;
     return;
   }
 
   promise->reject(exception_code, system_code, error_message);
 }
 
 void CdmPromiseAdapter::Clear() {
-  // Reject all outstanding promises.
+  // Reject all outstanding promises asynchronously. This is done as it
+  // may be triggered by gc in blink, and it doesn't like executing code
+  // while gc is running.
   DCHECK(thread_checker_.CalledOnValidThread());
-  for (auto& promise : promises_)
-    promise.second->reject(MediaKeys::UNKNOWN_ERROR, 0, "Operation aborted.");
+  while (promises_.begin() != promises_.end()) {
+    scoped_ptr<CdmPromise> promise(promises_.take_and_erase(promises_.begin()));
+    base::ThreadTaskRunnerHandle::Get()->PostTask(
+        FROM_HERE, base::Bind(&AbortPromise, base::Passed(&promise)));
+  }
   promises_.clear();
 }
 
 scoped_ptr<CdmPromise> CdmPromiseAdapter::TakePromise(uint32_t promise_id) {
   DCHECK(thread_checker_.CalledOnValidThread());
   PromiseMap::iterator it = promises_.find(promise_id);
   if (it == promises_.end())
     return nullptr;
   return promises_.take_and_erase(it);
 }
 
 // Explicit instantiation of function templates.
 template MEDIA_EXPORT void CdmPromiseAdapter::ResolvePromise(uint32_t);
 template MEDIA_EXPORT void CdmPromiseAdapter::ResolvePromise(
     uint32_t,
     const std::string&);
 
 }  // namespace media