[tracing] Add trace events filtering predicate for heap profiler

base/trace_event/trace_config.cc

Index: base/trace_event/trace_config.cc
diff --git a/base/trace_event/trace_config.cc b/base/trace_event/trace_config.cc
index 988f73a0343e4b35b6048521bb6ead3702a0a3b6..a98aefa70f356afb8b2bf63ddb1bbd3c297b2b82 100644
--- a/base/trace_event/trace_config.cc
+++ b/base/trace_event/trace_config.cc
@@ -629,6 +629,22 @@ void TraceConfig::SetDefaultMemoryDumpConfig() {
   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(