[tracing] Add filtering mode in TraceLog

base/trace_event/heap_profiler_allocation_context_tracker.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/heap_profiler_allocation_context_tracker.h"
 
 #include <algorithm>
 #include <iterator>
 
 #include "base/atomicops.h"
@@ skipping 111 matching lines @@
   // Guard for stack underflow. If tracing was started with a TRACE_EVENT in
   // scope, the frame was never pushed, so it is possible that pop is called
   // on an empty stack.
   if (pseudo_stack_.empty())
     return;
 
   // Assert that pushes and pops are nested correctly. This DCHECK can be
   // hit if some TRACE_EVENT macro is unbalanced (a TRACE_EVENT_END* call
   // without a corresponding TRACE_EVENT_BEGIN).
   DCHECK(stack_frame == pseudo_stack_.back())
-      << "Encountered an unmatched TRACE_EVENT_END";
+      << "Encountered an unmatched TRACE_EVENT_END: "
+      << stack_frame.trace_event_name
+      << ", event in stack: " << pseudo_stack_.back().trace_event_name;

[Primiano Tucci (use gerrit), 2016/09/23 18:34:31]

I'd probably s/,/vs/

[ssid, 2016/09/26 18:39:53]

Done.

 
   pseudo_stack_.pop_back();
 }
 
 void AllocationContextTracker::PushCurrentTaskContext(const char* context) {
   DCHECK(context);
   if (task_contexts_.size() < kMaxTaskDepth)
     task_contexts_.push_back(context);
   else
     NOTREACHED();
@@ skipping 101 matching lines @@
     // If task context was unavailable, then the category names are taken from
     // trace events.
     ctx.type_name = pseudo_stack_.back().trace_event_category;
   }
 
   return ctx;
 }
 
 }  // namespace trace_event
 }  // namespace base