tracing: split trace event filter classes out of TraceLog

base/trace_event/heap_profiler_event_filter.cc

Index: base/trace_event/heap_profiler_event_filter.cc
diff --git a/base/trace_event/heap_profiler_event_filter.cc b/base/trace_event/heap_profiler_event_filter.cc
new file mode 100644
index 0000000000000000000000000000000000000000..b666f19581275efe2497afb4e9b5d97adaed218d
--- /dev/null
+++ b/base/trace_event/heap_profiler_event_filter.cc
@@ -0,0 +1,60 @@
+// Copyright 2016 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_event_filter.h"
+
+#include "base/trace_event/category_registry.h"
+#include "base/trace_event/heap_profiler_allocation_context_tracker.h"
+#include "base/trace_event/trace_category.h"
+#include "base/trace_event/trace_event.h"
+#include "base/trace_event/trace_event_impl.h"
+
+namespace base {
+namespace trace_event {
+
+// static
+const char HeapProfilerEventFilter::kName[] = "heap_profiler_predicate";
+
+HeapProfilerEventFilter::HeapProfilerEventFilter() {}
+HeapProfilerEventFilter::~HeapProfilerEventFilter() {}
+
+bool HeapProfilerEventFilter::FilterTraceEvent(
+    const TraceEvent& trace_event) const {
+  if (AllocationContextTracker::capture_mode() !=

[oystein (OOO til 10th of July), 2016/12/08 20:40:20]

This class name is adding a lot of verbosity; would it be clearer if we had
something like "using act = AllocationContextTracker;"? Can't figure out if the
style guide has an opinion on this or not.

[Primiano Tucci (use gerrit), 2016/12/09 11:50:09]

I looked on the codebase and didn't find too much precedent *.
However I think I solved this by adding two inline getters on the top, so this
entire TU should now be more readable.


*
https://cs.chromium.org/search/?q=%5Eusing%5C+%5Cw%7B1,8%7D%5C+%5C%3D%5C+%5Cw...

+      AllocationContextTracker::CaptureMode::PSEUDO_STACK) {
+    return true;
+  }
+
+  // TODO(primiano): Add support for events with copied name crbug.com/581079.
+  if (trace_event.flags() & TRACE_EVENT_FLAG_COPY)
+    return true;
+
+  const char* category_name = CategoryRegistry::GetCategoryByStatePtr(
+                                  trace_event.category_group_enabled())
+                                  ->name();
+  if (trace_event.phase() == TRACE_EVENT_PHASE_BEGIN ||
+      trace_event.phase() == TRACE_EVENT_PHASE_COMPLETE) {
+    AllocationContextTracker::GetInstanceForCurrentThread()
+        ->PushPseudoStackFrame({category_name, trace_event.name()});
+  } else if (trace_event.phase() == TRACE_EVENT_PHASE_END) {
+    // The pop for |TRACE_EVENT_PHASE_COMPLETE| events is in |EndEvent|.
+    AllocationContextTracker::GetInstanceForCurrentThread()
+        ->PopPseudoStackFrame({category_name, trace_event.name()});
+  }
+  // Do not filter-out any events and always return true. TraceLog adds the
+  // event only if it is enabled for recording.
+  return true;
+}
+
+void HeapProfilerEventFilter::EndEvent(const char* category_name,
+                                       const char* event_name) const {
+  if (AllocationContextTracker::capture_mode() ==
+      AllocationContextTracker::CaptureMode::PSEUDO_STACK) {
+    AllocationContextTracker::GetInstanceForCurrentThread()
+        ->PopPseudoStackFrame({category_name, event_name});
+  }
+}
+
+}  // namespace trace_event
+}  // namespace base