[tracing] Introduce support for userland memory allocators dumps.

base/trace_event/memory_allocator_dump.cc

Index: base/trace_event/memory_allocator_dump.cc
diff --git a/base/trace_event/memory_allocator_dump.cc b/base/trace_event/memory_allocator_dump.cc
new file mode 100644
index 0000000000000000000000000000000000000000..1f89632c2d8ed1317efec91fcc6699d3035cdb4b
--- /dev/null
+++ b/base/trace_event/memory_allocator_dump.cc
@@ -0,0 +1,50 @@
+// 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/memory_allocator_dump.h"
+
+#include "base/format_macros.h"
+#include "base/trace_event/trace_event_argument.h"
+#include "base/values.h"
+
+namespace base {
+namespace trace_event {
+
+MemoryAllocatorDump::MemoryAllocatorDump(const std::string& name,
+                                         MemoryAllocatorDump* parent)
+    : name_(name), parent_(parent) {
+}
+
+MemoryAllocatorDump::~MemoryAllocatorDump() {
+}
+
+void MemoryAllocatorDump::AsValueInto(TracedValue* value) const {
+  value->BeginDictionary(name_.c_str());
+
+  value->SetString("parent", parent_ ? parent_->name_ : "");
+  value->SetInteger("physical_size", physical_size_in_bytes_);
+  value->SetInteger("allocated_objects_count", allocated_objects_count_);
+  value->SetInteger("allocated_objects_size", allocated_objects_size_in_bytes_);
+
+  // Copy all the extra attributes.
+  value->BeginDictionary("args");
+  for (DictionaryValue::Iterator it(extra_attributes_); !it.IsAtEnd();
+       it.Advance()) {
+    const std::string& attr_name = it.key();
+    const Value& attr_value = it.value();
+    value->BeginDictionary(attr_name.c_str());
+    value->SetValue("value", attr_value.DeepCopy());
+
+    DCHECK(extra_attributes_types_ && extra_attributes_types_->Get(attr_name));
+    value->SetString("type", extra_attributes_types_->Get(attr_name)->type);
+
+    value->EndDictionary();  // "arg_name": { "type": "...", "value": "..." }
+  }
+  value->EndDictionary();  // "args": {}
+
+  value->EndDictionary();  // "allocator name": {}
+}
+
+}  // namespace trace_event
+}  // namespace base