[tracing] Add browser test for background memory tracing

content/child/child_discardable_shared_memory_manager.cc

 // Copyright 2014 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 "content/child/child_discardable_shared_memory_manager.h"
 
+#include <inttypes.h>
+
 #include <algorithm>
 #include <utility>
 
 #include "base/atomic_sequence_num.h"
 #include "base/bind.h"
 #include "base/debug/crash_logging.h"
 #include "base/macros.h"
 #include "base/memory/discardable_memory.h"
 #include "base/memory/discardable_shared_memory.h"
 #include "base/memory/ptr_util.h"
 #include "base/metrics/histogram.h"
 #include "base/process/memory.h"
 #include "base/process/process_metrics.h"
 #include "base/strings/string_number_conversions.h"
+#include "base/strings/stringprintf.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/trace_event/memory_dump_manager.h"
 #include "base/trace_event/trace_event.h"
 #include "content/common/child_process_messages.h"
 
 namespace content {
 namespace {
 
 // Default allocation size.
 const size_t kAllocationSize = 4 * 1024 * 1024;
@@ skipping 179 matching lines @@
   return base::WrapUnique(new DiscardableMemoryImpl(this, std::move(new_span)));
 }
 
 bool ChildDiscardableSharedMemoryManager::OnMemoryDump(
     const base::trace_event::MemoryDumpArgs& args,
     base::trace_event::ProcessMemoryDump* pmd) {
   base::AutoLock lock(lock_);
   if (args.level_of_detail ==
       base::trace_event::MemoryDumpLevelOfDetail::BACKGROUND) {
     base::trace_event::MemoryAllocatorDump* total_dump =
-        pmd->CreateAllocatorDump("discardable");
+        pmd->CreateAllocatorDump(
+            base::StringPrintf("discardable/child_0x%" PRIXPTR,
+                               reinterpret_cast<uintptr_t>(this)));
     const size_t total_size = heap_.GetSize();
     const size_t freelist_size = heap_.GetSizeOfFreeLists();
     total_dump->AddScalar(base::trace_event::MemoryAllocatorDump::kNameSize,
                           base::trace_event::MemoryAllocatorDump::kUnitsBytes,
                           total_size - freelist_size);
     total_dump->AddScalar("freelist_size",
                           base::trace_event::MemoryAllocatorDump::kUnitsBytes,
                           freelist_size);
     return true;
   }
@@ skipping 104 matching lines @@
       "discardable-memory-allocated";
   base::debug::SetCrashKeyValue(kDiscardableMemoryAllocatedKey,
                                 base::Uint64ToString(new_bytes_total));
 
   static const char kDiscardableMemoryFreeKey[] = "discardable-memory-free";
   base::debug::SetCrashKeyValue(kDiscardableMemoryFreeKey,
                                 base::Uint64ToString(new_bytes_free));
 }
 
 }  // namespace content