Revert of base: Remove use of MessageLoopProxy

base/trace_event/trace_event_impl.cc

 // Copyright (c) 2012 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/trace_event/trace_event_impl.h"
 
 #include <algorithm>
 #include <cmath>
 
 #include "base/base_switches.h"
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/debug/leak_annotations.h"
 #include "base/format_macros.h"
 #include "base/json/string_escape.h"
 #include "base/lazy_instance.h"
-#include "base/location.h"
 #include "base/memory/singleton.h"
+#include "base/message_loop/message_loop.h"
 #include "base/process/process_metrics.h"
 #include "base/stl_util.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_split.h"
 #include "base/strings/string_tokenizer.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/synchronization/cancellation_flag.h"
 #include "base/synchronization/waitable_event.h"
 #include "base/sys_info.h"
 #include "base/third_party/dynamic_annotations/dynamic_annotations.h"
-#include "base/thread_task_runner_handle.h"
 #include "base/threading/platform_thread.h"
 #include "base/threading/thread_id_name_manager.h"
 #include "base/threading/worker_pool.h"
 #include "base/time/time.h"
 #include "base/trace_event/trace_event.h"
 #include "base/trace_event/trace_event_synthetic_delay.h"
 
 #if defined(OS_WIN)
 #include "base/trace_event/trace_event_etw_export_win.h"
 #include "base/trace_event/trace_event_win.h"
@@ skipping 1358 matching lines @@
 }
 
 void TraceLog::SetEnabled(const CategoryFilter& category_filter,
                           Mode mode,
                           const TraceOptions& options) {
   std::vector<EnabledStateObserver*> observer_list;
   {
     AutoLock lock(lock_);
 
     // Can't enable tracing when Flush() is in progress.
-    DCHECK(!flush_task_runner_);
+    DCHECK(!flush_message_loop_proxy_.get());
 
     InternalTraceOptions new_options =
         GetInternalOptionsFromTraceOptions(options);
 
    InternalTraceOptions old_options = trace_options();
 
     if (IsEnabled()) {
       if (new_options != old_options) {
         DLOG(ERROR) << "Attempting to re-enable tracing with a different "
                     << "set of options.";
@@ skipping 253 matching lines @@
   UpdateCategoryGroupEnabledFlags();
 };
 
 void TraceLog::SetEventCallbackDisabled() {
   AutoLock lock(lock_);
   subtle::NoBarrier_Store(&event_callback_, 0);
   UpdateCategoryGroupEnabledFlags();
 }
 
 // Flush() works as the following:
-// 1. Flush() is called in thread A whose task runner is saved in
-//    flush_task_runner_;
-// 2. If thread_message_loops_ is not empty, thread A posts task to each message
+// 1. Flush() is called in threadA whose message loop is saved in
+//    flush_message_loop_proxy_;
+// 2. If thread_message_loops_ is not empty, threadA posts task to each message
 //    loop to flush the thread local buffers; otherwise finish the flush;
 // 3. FlushCurrentThread() deletes the thread local event buffer:
 //    - The last batch of events of the thread are flushed into the main buffer;
 //    - The message loop will be removed from thread_message_loops_;
 //    If this is the last message loop, finish the flush;
 // 4. If any thread hasn't finish its flush in time, finish the flush.
 void TraceLog::Flush(const TraceLog::OutputCallback& cb,
                      bool use_worker_thread) {
   use_worker_thread_ = use_worker_thread;
   if (IsEnabled()) {
     // Can't flush when tracing is enabled because otherwise PostTask would
     // - generate more trace events;
     // - deschedule the calling thread on some platforms causing inaccurate
     //   timing of the trace events.
     scoped_refptr<RefCountedString> empty_result = new RefCountedString;
     if (!cb.is_null())
       cb.Run(empty_result, false);
     LOG(WARNING) << "Ignored TraceLog::Flush called when tracing is enabled";
     return;
   }
 
   int generation = this->generation();
   // Copy of thread_message_loops_ to be used without locking.
   std::vector<scoped_refptr<SingleThreadTaskRunner> >
       thread_message_loop_task_runners;
   {
     AutoLock lock(lock_);
-    DCHECK(!flush_task_runner_);
-    flush_task_runner_ = ThreadTaskRunnerHandle::IsSet()
-                             ? ThreadTaskRunnerHandle::Get()
-                             : nullptr;
-    DCHECK_IMPLIES(thread_message_loops_.size(), flush_task_runner_);
+    DCHECK(!flush_message_loop_proxy_.get());
+    flush_message_loop_proxy_ = MessageLoopProxy::current();
+    DCHECK(!thread_message_loops_.size() || flush_message_loop_proxy_.get());
     flush_output_callback_ = cb;
 
     if (thread_shared_chunk_) {
       logged_events_->ReturnChunk(thread_shared_chunk_index_,
                                   thread_shared_chunk_.Pass());
     }
 
     if (thread_message_loops_.size()) {
       for (hash_set<MessageLoop*>::const_iterator it =
            thread_message_loops_.begin();
            it != thread_message_loops_.end(); ++it) {
         thread_message_loop_task_runners.push_back((*it)->task_runner());
       }
     }
   }
 
   if (thread_message_loop_task_runners.size()) {
     for (size_t i = 0; i < thread_message_loop_task_runners.size(); ++i) {
       thread_message_loop_task_runners[i]->PostTask(
           FROM_HERE,
           Bind(&TraceLog::FlushCurrentThread, Unretained(this), generation));
     }
-    flush_task_runner_->PostDelayedTask(
+    flush_message_loop_proxy_->PostDelayedTask(
         FROM_HERE,
         Bind(&TraceLog::OnFlushTimeout, Unretained(this), generation),
         TimeDelta::FromMilliseconds(kThreadFlushTimeoutMs));
     return;
   }
 
   FinishFlush(generation);
 }
 
 // Usually it runs on a different thread.
@@ skipping 33 matching lines @@
   if (!CheckGeneration(generation))
     return;
 
   {
     AutoLock lock(lock_);
 
     previous_logged_events.swap(logged_events_);
     UseNextTraceBuffer();
     thread_message_loops_.clear();
 
-    flush_task_runner_ = NULL;
+    flush_message_loop_proxy_ = NULL;
     flush_output_callback = flush_output_callback_;
     flush_output_callback_.Reset();
   }
 
   if (use_worker_thread_ &&
       WorkerPool::PostTask(
           FROM_HERE,
           Bind(&TraceLog::ConvertTraceEventsToTraceFormat,
                Passed(&previous_logged_events),
                flush_output_callback),
           true)) {
     return;
   }
 
   ConvertTraceEventsToTraceFormat(previous_logged_events.Pass(),
                                   flush_output_callback);
 }
 
 // Run in each thread holding a local event buffer.
 void TraceLog::FlushCurrentThread(int generation) {
   {
     AutoLock lock(lock_);
-    if (!CheckGeneration(generation) || !flush_task_runner_) {
+    if (!CheckGeneration(generation) || !flush_message_loop_proxy_.get()) {
       // This is late. The corresponding flush has finished.
       return;
     }
   }
 
   // This will flush the thread local buffer.
   delete thread_local_event_buffer_.Get();
 
   AutoLock lock(lock_);
-  if (!CheckGeneration(generation) || !flush_task_runner_ ||
+  if (!CheckGeneration(generation) || !flush_message_loop_proxy_.get() ||
       thread_message_loops_.size())
     return;
 
-  flush_task_runner_->PostTask(
-      FROM_HERE, Bind(&TraceLog::FinishFlush, Unretained(this), generation));
+  flush_message_loop_proxy_->PostTask(
+      FROM_HERE,
+      Bind(&TraceLog::FinishFlush, Unretained(this), generation));
 }
 
 void TraceLog::OnFlushTimeout(int generation) {
   {
     AutoLock lock(lock_);
-    if (!CheckGeneration(generation) || !flush_task_runner_) {
+    if (!CheckGeneration(generation) || !flush_message_loop_proxy_.get()) {
       // Flush has finished before timeout.
       return;
     }
 
     LOG(WARNING) <<
         "The following threads haven't finished flush in time. "
         "If this happens stably for some thread, please call "
         "TraceLog::GetInstance()->SetCurrentThreadBlocksMessageLoop() from "
         "the thread to avoid its trace events from being lost.";
     for (hash_set<MessageLoop*>::const_iterator it =
@@ skipping 786 matching lines @@
 }
 
 ScopedTraceBinaryEfficient::~ScopedTraceBinaryEfficient() {
   if (*category_group_enabled_) {
     TRACE_EVENT_API_UPDATE_TRACE_EVENT_DURATION(category_group_enabled_,
                                                 name_, event_handle_);
   }
 }
 
 }  // namespace trace_event_internal