[tracing] Add a dump provider to dump process memory totals.

base/trace_event/process_memory_dump.h

Index: base/trace_event/process_memory_dump.h
diff --git a/base/trace_event/process_memory_dump.h b/base/trace_event/process_memory_dump.h
index ae42987dfd12cd86f9cfcf28343bb7391d2d6cf7..b47ca299b2ff91f9d5414a882d457e9947e678b2 100644
--- a/base/trace_event/process_memory_dump.h
+++ b/base/trace_event/process_memory_dump.h
@@ -12,6 +12,8 @@
 namespace base {
 namespace trace_event {
 
+class ProcessMemoryTotals;
+
 // A container which holds the dumps produced by the MemoryDumpProvider(s)
 // for a specific process. ProcessMemoryDump is as a strongly typed container
 // which enforces the data model for each memory dump point.
@@ -25,7 +27,15 @@ class BASE_EXPORT ProcessMemoryDump : public ConvertableToTraceFormat {
   // ConvertableToTraceFormat implementation.
   void AppendAsTraceFormat(std::string* out) const override;
 
+  void SetProcessTotals(scoped_ptr<ProcessMemoryTotals> pmt);
+
+  const ProcessMemoryTotals* process_totals() const {
+    return process_totals_.get();
+  }
+
  private:
+  scoped_ptr<ProcessMemoryTotals> process_totals_;
+
   ~ProcessMemoryDump() override;
 
   DISALLOW_COPY_AND_ASSIGN(ProcessMemoryDump);