[Tentaive patch for discussion] Add Purge+Suspend metrics as UMA.

base/trace_event/malloc_dump_provider.h

Index: base/trace_event/malloc_dump_provider.h
diff --git a/base/trace_event/malloc_dump_provider.h b/base/trace_event/malloc_dump_provider.h
index 384033c9b82abc55125405e9a29ede7aa9597c08..e8b9e5f99199b9abbbb2a4b70ab7553b240896bb 100644
--- a/base/trace_event/malloc_dump_provider.h
+++ b/base/trace_event/malloc_dump_provider.h
@@ -25,6 +25,21 @@ namespace trace_event {
 
 class AllocationRegister;
 
+struct MallocStatistics {
+  size_t allocated_objects_size;
+  size_t allocated_objects_count;
+  size_t metadata_fragmentation_caches;
+  size_t total_virtual_size;
+  size_t resident_size;
+
+  MallocStatistics()
+      : allocated_objects_size(0),
+        allocated_objects_count(0),
+        metadata_fragmentation_caches(0),
+        total_virtual_size(0),
+        resident_size(0) {}
+};
+
 // Dump provider which collects process-wide memory stats.
 class BASE_EXPORT MallocDumpProvider : public MemoryDumpProvider {
  public:
@@ -34,6 +49,8 @@ class BASE_EXPORT MallocDumpProvider : public MemoryDumpProvider {
 
   static MallocDumpProvider* GetInstance();
 
+  static MallocStatistics GetStatistics();
+
   // MemoryDumpProvider implementation.
   bool OnMemoryDump(const MemoryDumpArgs& args,
                     ProcessMemoryDump* pmd) override;