android: Add thread time to early TraceEvent, make timings more precise.

base/trace_event/trace_log.cc

 // Copyright 2015 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_log.h"
 
 #include <algorithm>
 #include <cmath>
 #include <memory>
 #include <utility>
@@ skipping 1363 matching lines @@
 }
 
 void TraceLog::UpdateTraceEventDuration(
     const unsigned char* category_group_enabled,
     const char* name,
     TraceEventHandle handle) {
   char category_group_enabled_local = *category_group_enabled;
   if (!category_group_enabled_local)
     return;
 
+  TimeTicks now = OffsetNow();
+  ThreadTicks thread_now = ThreadNow();
+  UpdateTraceEventDurationExplicit(category_group_enabled, name, handle, now,

[Primiano Tucci (use gerrit), 2017/07/10 13:09:15]

small nit: given that this wraps already, you could just do the *Now() calls
inline. not sure the temporary variables add any benefit here.

[Benoit L, 2017/07/10 13:39:54]

Done.

+                                   thread_now);
+}
+
+void TraceLog::UpdateTraceEventDurationExplicit(
+    const unsigned char* category_group_enabled,
+    const char* name,
+    TraceEventHandle handle,
+    const TimeTicks& now,
+    const ThreadTicks& thread_now) {
+  char category_group_enabled_local = *category_group_enabled;
+  if (!category_group_enabled_local)
+    return;
+
   // Avoid re-entrance of AddTraceEvent. This may happen in GPU process when
   // ECHO_TO_CONSOLE is enabled: AddTraceEvent -> LOG(ERROR) ->
   // GpuProcessLogMessageHandler -> PostPendingTask -> TRACE_EVENT ...
   if (thread_is_in_trace_event_.Get())
     return;
-
   AutoThreadLocalBoolean thread_is_in_trace_event(&thread_is_in_trace_event_);
 
-  ThreadTicks thread_now = ThreadNow();
-  TimeTicks now = OffsetNow();
-
 #if defined(OS_WIN)
   // Generate an ETW event that marks the end of a complete event.
   if (category_group_enabled_local & TraceCategory::ENABLED_FOR_ETW_EXPORT)
     TraceEventETWExport::AddCompleteEndEvent(name);
 #endif  // OS_WIN
 
   std::string console_message;
   if (category_group_enabled_local & TraceCategory::ENABLED_FOR_RECORDING) {
     OptionalAutoLock lock(&lock_);
 
@@ skipping 297 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