[tracing] Add method to create "weak" global dumps

base/trace_event/memory_allocator_dump.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/memory_allocator_dump.h"
 
 #include "base/format_macros.h"
 #include "base/strings/stringprintf.h"
 #include "base/trace_event/memory_dump_manager.h"
 #include "base/trace_event/memory_dump_provider.h"
@@ skipping 10 matching lines @@
 const char MemoryAllocatorDump::kTypeString[] = "string";
 const char MemoryAllocatorDump::kUnitsBytes[] = "bytes";
 const char MemoryAllocatorDump::kUnitsObjects[] = "objects";
 
 MemoryAllocatorDump::MemoryAllocatorDump(const std::string& absolute_name,
                                          ProcessMemoryDump* process_memory_dump,
                                          const MemoryAllocatorDumpGuid& guid)
     : absolute_name_(absolute_name),
       process_memory_dump_(process_memory_dump),
       attributes_(new TracedValue),
-      guid_(guid) {
+      guid_(guid),
+      flags_(Flags::DEFAULT) {
   // The |absolute_name| cannot be empty.
   DCHECK(!absolute_name.empty());
 
   // The |absolute_name| can contain slash separator, but not leading or
   // trailing ones.
   DCHECK(absolute_name[0] != '/' && *absolute_name.rbegin() != '/');
 }
 
 // If the caller didn't provide a guid, make one up by hashing the
 // absolute_name with the current PID.
@@ skipping 41 matching lines @@
   attributes_->SetString("type", kTypeString);
   attributes_->SetString("units", units);
   attributes_->SetString("value", value);
   attributes_->EndDictionary();
 }
 
 void MemoryAllocatorDump::AsValueInto(TracedValue* value) const {
   value->BeginDictionaryWithCopiedName(absolute_name_);
   value->SetString("guid", guid_.ToString());
   value->SetValue("attrs", *attributes_);
+  if (flags_)
+    value->SetInteger("flags", flags_);
   value->EndDictionary();  // "allocator_name/heap_subheap": { ... }
 }
 
 }  // namespace trace_event
 }  // namespace base