[Merge to 3071] Add the UMA metric Memory.Gpu.PhysicalFootprint.MacOS

base/process/process_metrics.h

Index: base/process/process_metrics.h
diff --git a/base/process/process_metrics.h b/base/process/process_metrics.h
index 9c1ea9d9281dea2f780b2d6375806888b2b68a61..6e5e796a7c825be5d390d0b79fdd9ac373d45ae0 100644
--- a/base/process/process_metrics.h
+++ b/base/process/process_metrics.h
@@ -166,6 +166,12 @@ class BASE_EXPORT ProcessMetrics {
   // system call.
   bool GetCommittedAndWorkingSetKBytes(CommittedKBytes* usage,
                                        WorkingSetKBytes* ws_usage) const;
+
+  // Returns the physical footprint, only available on macOS 10.11+. This
+  // measures anonymous, non-discardable memory. Returns 0 on error, or if the
+  // measurement was unavailable.
+  size_t GetPhysicalFootprint() const;
+
   // Returns private, shared, and total resident bytes. |locked_bytes| refers to
   // bytes that must stay resident. |locked_bytes| only counts bytes locked by
   // this task, not bytes locked by the kernel.