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

base/memory/shared_memory_tracker.h

Index: base/memory/shared_memory_tracker.h
diff --git a/base/memory/shared_memory_tracker.h b/base/memory/shared_memory_tracker.h
index fe1a3dd392177b0c20bb5b2daf6498d85eae7e0b..8ec5e4cd9fbd034fb73fc76813b92699d9dcd4b2 100644
--- a/base/memory/shared_memory_tracker.h
+++ b/base/memory/shared_memory_tracker.h
@@ -12,9 +12,11 @@
 namespace base {
 
 namespace trace_event {
+class MemoryAllocatorDumpGuid;
 class ProcessMemoryDump;
 }
 
+#if !defined(OS_NACL)
 // SharedMemoryTracker tracks shared memory usage.
 class BASE_EXPORT SharedMemoryTracker
     : public base::trace_event::MemoryDumpProvider {
@@ -22,6 +24,13 @@ class BASE_EXPORT SharedMemoryTracker
   // Returns a singleton instance.
   static SharedMemoryTracker* GetInstance();
 
+  // TODO: Importances
+  static bool AddOwnershipEdges(
+      trace_event::ProcessMemoryDump* pmd,
+      const trace_event::MemoryAllocatorDumpGuid& source,
+      const SharedMemoryHandle& shared_memory_handle,
+      size_t mapped_size);
+
   // Records shared memory usage on mapping.
   void IncrementMemoryUsage(const SharedMemory& shared_memory);
 
@@ -41,8 +50,8 @@ class BASE_EXPORT SharedMemoryTracker
   ~SharedMemoryTracker() override;
 
   // base::trace_event::MemoryDumpProvider implementation.
-  bool OnMemoryDump(const base::trace_event::MemoryDumpArgs& args,
-                    base::trace_event::ProcessMemoryDump* pmd) override;
+  bool OnMemoryDump(const trace_event::MemoryDumpArgs& args,
+                    trace_event::ProcessMemoryDump* pmd) override;
 
   // Used to lock when |usages_| is modified or read.
   Lock usages_lock_;
@@ -51,6 +60,33 @@ class BASE_EXPORT SharedMemoryTracker
   DISALLOW_COPY_AND_ASSIGN(SharedMemoryTracker);
 };
 
+#else
+
+class BASE_EXPORT SharedMemoryTracker {
+ public:
+  static SharedMemoryTracker* GetInstance() {
+    static SharedMemoryTracker* instance = new SharedMemoryTracker;
+    return instance;
+  }
+
+  // TODO: Importances
+  static bool AddOwnershipEdges(
+      trace_event::ProcessMemoryDump* pmd,
+      const trace_event::MemoryAllocatorDumpGuid& source,
+      const SharedMemoryHandle& shared_memory_handle,
+      size_t mapped_size) {
+    return true;
+  }
+
+  // Records shared memory usage on mapping.
+  void IncrementMemoryUsage(const SharedMemory& shared_memory) {}
+
+  // Records shared memory usage on unmapping.
+  void DecrementMemoryUsage(const SharedMemory& shared_memory) {}
+};
+
+#endif  // !defined(OS_NACL)
+
 }  // namespace base
 
 #endif  // BASE_MEMORY_SHARED_MEMORY_TRACKER_H_