Disallow nesting on some BrowserThreads.

base/message_loop/message_loop.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 "base/message_loop/message_loop.h"
 
 #include <algorithm>
 #include <utility>
 
 #include "base/bind.h"
@@ skipping 198 matching lines @@
 }
 
 void MessageLoop::RemoveDestructionObserver(
     DestructionObserver* destruction_observer) {
   DCHECK_EQ(this, current());
   destruction_observers_.RemoveObserver(destruction_observer);
 }
 
 void MessageLoop::AddNestingObserver(NestingObserver* observer) {
   DCHECK_EQ(this, current());
+  CHECK(allow_nesting_);
   nesting_observers_.AddObserver(observer);
 }
 
 void MessageLoop::RemoveNestingObserver(NestingObserver* observer) {
   DCHECK_EQ(this, current());
+  CHECK(allow_nesting_);
   nesting_observers_.RemoveObserver(observer);
 }
 
 void MessageLoop::QuitWhenIdle() {
   DCHECK_EQ(this, current());
   if (run_loop_) {
     run_loop_->QuitWhenIdle();
   } else {
     NOTREACHED() << "Must be inside Run to call QuitWhenIdle";
   }
@@ skipping 16 matching lines @@
   MessageLoop::current()->QuitWhenIdle();
 }
 
 // static
 Closure MessageLoop::QuitWhenIdleClosure() {
   return Bind(&QuitCurrentWhenIdle);
 }
 
 void MessageLoop::SetNestableTasksAllowed(bool allowed) {
   if (allowed) {
+    CHECK(allow_nesting_);
+
     // Kick the native pump just in case we enter a OS-driven nested message
     // loop.
     pump_->ScheduleWork();
   }
   nestable_tasks_allowed_ = allowed;
 }
 
 bool MessageLoop::NestableTasksAllowed() const {
   return nestable_tasks_allowed_;
 }
@@ skipping 90 matching lines @@
 void MessageLoop::SetThreadTaskRunnerHandle() {
   DCHECK_EQ(this, current());
   // Clear the previous thread task runner first, because only one can exist at
   // a time.
   thread_task_runner_handle_.reset();
   thread_task_runner_handle_.reset(new ThreadTaskRunnerHandle(task_runner_));
 }
 
 void MessageLoop::RunHandler() {
   DCHECK_EQ(this, current());
+  DCHECK(run_loop_);
+  CHECK(allow_nesting_ || run_loop_->run_depth_ == 1);
   pump_->Run(this);
 }
 
 bool MessageLoop::ProcessNextDelayedNonNestableTask() {
   if (run_loop_->run_depth_ != 1)
     return false;
 
   if (deferred_non_nestable_work_queue_.empty())
     return false;
 
@@ skipping 266 matching lines @@
       persistent,
       mode,
       controller,
       delegate);
 }
 #endif
 
 #endif  // !defined(OS_NACL_SFI)
 
 }  // namespace base