[tracing] Add trace events filtering predicate for heap profiler

base/trace_event/trace_config.cc

 // Copyright (c) 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_config.h"
 
 #include <stddef.h>
 
 #include <utility>
 
@@ skipping 611 matching lines @@
           MemoryDumpConfig::HeapProfiler::kDefaultBreakdownThresholdBytes;
     }
   }
 }
 
 void TraceConfig::SetDefaultMemoryDumpConfig() {
   memory_dump_config_.Clear();
   memory_dump_config_.triggers.push_back(kDefaultHeavyMemoryDumpTrigger);
   memory_dump_config_.triggers.push_back(kDefaultLightMemoryDumpTrigger);
   memory_dump_config_.allowed_dump_modes = GetDefaultAllowedMemoryDumpModes();
+
+  if (AllocationContextTracker::capture_mode() ==
+      AllocationContextTracker::CaptureMode::PSEUDO_STACK) {
+    for (const auto& filter : event_filters_) {
+      if (filter.predicate_name() ==
+          TraceLog::TraceEventFilter::kHeapProfilerPredicate)
+        return;
+    }
+    // Adds a filter predicate to filter all categories for the heap profiler.
+    // Note that the heap profiler predicate does not filter any events.

[Primiano Tucci (use gerrit), 2016/08/24 10:33:46]

s/filter/filter-out/, so it's easier to understand that what you mean here is
the fact that you let all filters pass through.

[ssid, 2016/08/24 18:01:25]

Done.

+    EventFilterConfig heap_profiler_config(
+        TraceLog::TraceEventFilter::kHeapProfilerPredicate);
+    heap_profiler_config.AddIncludedCategory("*");
+    heap_profiler_config.AddIncludedCategory(MemoryDumpManager::kTraceCategory);

[Primiano Tucci (use gerrit), 2016/08/24 10:33:46]

do you really need to see the memory-infra events for the heap profiler?

[ssid, 2016/08/24 18:01:25]

Actually this line is not required. But I added this just to be safe.
There could have been a case where the "memory-infra" events were enabled for
filtering but not being filtered by "heap_profiler_predicate" and some other
filter removed these events. This might cause the memory dump events to go
missing from the trace.

+    event_filters_.push_back(heap_profiler_config);
+  }
 }
 
 void TraceConfig::SetEventFilters(
     const base::ListValue& category_event_filters) {
   event_filters_.clear();
 
   for (size_t event_filter_index = 0;
        event_filter_index < category_event_filters.GetSize();
        ++event_filter_index) {
     const base::DictionaryValue* event_filter = nullptr;
@@ skipping 210 matching lines @@
     StringPiece str) {
   return str.empty() || str.front() == ' ' || str.back() == ' ';
 }
 
 bool TraceConfig::HasIncludedPatterns() const {
   return !included_categories_.empty();
 }
 
 }  // namespace trace_event
 }  // namespace base