[WIP] Add SharedMemoryTracker to dump base::SharedMemory usage

base/memory/shared_memory_tracker.cc

Index: base/memory/shared_memory_tracker.cc
diff --git a/base/memory/shared_memory_tracker.cc b/base/memory/shared_memory_tracker.cc
new file mode 100644
index 0000000000000000000000000000000000000000..323c8e775a3fb90d4ff77e637182a13ece8d4ecd
--- /dev/null
+++ b/base/memory/shared_memory_tracker.cc
@@ -0,0 +1,109 @@
+// Copyright 2017 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/memory/shared_memory_tracker.h"
+
+#include "base/memory/shared_memory.h"
+#include "base/strings/stringprintf.h"
+#include "base/trace_event/memory_dump_manager.h"
+#include "base/trace_event/process_memory_dump.h"
+
+namespace base {
+
+const char* kSharedMemoryDumpName = "sharedmemory";
+
+SharedMemoryTracker* SharedMemoryTracker::GetInstance() {
+  return base::Singleton<SharedMemoryTracker, base::LeakySingletonTraits<
+                                                  SharedMemoryTracker>>::get();
+}
+
+bool SharedMemoryTracker::AddOwnershipEdgeToSharedGlobalDump(
+    trace_event::ProcessMemoryDump* pmd,
+    const trace_event::MemoryAllocatorDumpGuid& source,
+    const SharedMemoryHandle& shared_memory_handle,
+    size_t mapped_size) {
+  SharedMemoryHandleID id;
+  if (!GetIDFromSharedMemoryHandle(shared_memory_handle, &id)) {
+    return false;
+  }
+  std::string id_str = GetSharedMemoryHandleIDString(id);
+  std::string dump_name =
+      base::StringPrintf("%s/%s", kSharedMemoryDumpName, id_str.c_str());
+  auto global_dump = pmd->CreateSharedGlobalAllocatorDump(
+      base::trace_event::MemoryAllocatorDumpGuid(dump_name));
+  global_dump->AddScalar(base::trace_event::MemoryAllocatorDump::kNameSize,
+                         base::trace_event::MemoryAllocatorDump::kUnitsBytes,
+                         mapped_size);
+  pmd->AddOwnershipEdge(source, global_dump->guid());
+  return true;
+}
+
+bool SharedMemoryTracker::OnMemoryDump(
+    const base::trace_event::MemoryDumpArgs& args,
+    base::trace_event::ProcessMemoryDump* pmd) {
+  for (auto& bucket : buckets_) {
+    base::AutoLock lock(bucket.lock);
+    for (const auto& usage_in_device : bucket.usage) {
+      for (const auto& usage : usage_in_device.second) {
+        SharedMemoryHandleID id;
+        id.device_id = usage_in_device.first;
+        id.file_id = usage.first;
+        std::string id_str = GetSharedMemoryHandleIDString(id);
+        std::string dump_name =
+            base::StringPrintf("%s/%s", kSharedMemoryDumpName, id_str.c_str());
+        auto guid = base::trace_event::MemoryAllocatorDumpGuid(dump_name);
+        base::trace_event::MemoryAllocatorDump* local_dump =
+            pmd->CreateAllocatorDump(dump_name);
+        local_dump->AddScalar(
+            base::trace_event::MemoryAllocatorDump::kNameSize,
+            base::trace_event::MemoryAllocatorDump::kUnitsBytes, usage.second);
+        base::trace_event::MemoryAllocatorDump* global_dump =
+            pmd->CreateSharedGlobalAllocatorDump(guid);
+        global_dump->AddScalar(
+            base::trace_event::MemoryAllocatorDump::kNameSize,
+            base::trace_event::MemoryAllocatorDump::kUnitsBytes, usage.second);
+        pmd->AddOwnershipEdge(local_dump->guid(), global_dump->guid());
+      }
+    }
+  }
+  return true;
+}
+
+bool SharedMemoryTracker::IncrementMemoryUsage(
+    const SharedMemory& shared_memory) {
+  SharedMemoryHandleID id;
+  if (!GetIDFromSharedMemoryHandle(shared_memory.handle(), &id)) {
+    return false;
+  }
+  int bucket = id.file_id % kTrackerBucketNum;
+  base::AutoLock lock(buckets_[bucket].lock);
+  buckets_[bucket].usage[id.device_id][id.file_id] =
+      shared_memory.mapped_size();
+  return true;
+}
+
+bool SharedMemoryTracker::DecrementMemoryUsage(
+    const SharedMemory& shared_memory) {
+  SharedMemoryHandleID id;
+  if (!GetIDFromSharedMemoryHandle(shared_memory.handle(), &id)) {
+    return false;
+  }
+  int bucket = id.file_id % kTrackerBucketNum;
+  base::AutoLock lock(buckets_[bucket].lock);
+  buckets_[bucket].usage[id.device_id].erase(id.file_id);
+  return true;
+}
+
+SharedMemoryTracker::SharedMemoryTracker() {
+  base::trace_event::MemoryDumpManager::GetInstance()->RegisterDumpProvider(
+      this, "SharedMemoryTracker", nullptr);
+}
+
+SharedMemoryTracker::~SharedMemoryTracker() {}
+
+SharedMemoryTracker::TrackerBucket::TrackerBucket() {}
+
+SharedMemoryTracker::TrackerBucket::~TrackerBucket() {}
+
+}  // namespace