Add function to compute proportional set size for OS_WIN

components/tracing/common/process_metrics_memory_dump_provider.cc

Index: components/tracing/common/process_metrics_memory_dump_provider.cc
diff --git a/components/tracing/common/process_metrics_memory_dump_provider.cc b/components/tracing/common/process_metrics_memory_dump_provider.cc
index d2c00c347f0db3f7f9b13286e2af3edc4ac089b3..cb1db79abc5f27b091b21ec4824765a1c98e6469 100644
--- a/components/tracing/common/process_metrics_memory_dump_provider.cc
+++ b/components/tracing/common/process_metrics_memory_dump_provider.cc
@@ -298,7 +298,19 @@ bool ProcessMetricsMemoryDumpProvider::DumpProcessTotals(
                                               nullptr /* shared_bytes */);
   if (res)
     pmd->process_totals()->SetExtraFieldInBytes("private_bytes", private_bytes);
-#endif  // defined(OS_LINUX) || defined(OS_ANDROID)
+#elif defined(OS_WIN)
+  if (args.level_of_detail ==
+      base::trace_event::MemoryDumpLevelOfDetail::DETAILED) {
+    uint64_t pss_bytes = 0;
+    bool res = process_metrics_->GetProportionalSetSizeBytes(&pss_bytes);
+    if (res) {
+      base::trace_event::ProcessMemoryMaps::VMRegion region;
+      region.byte_stats_proportional_resident = pss_bytes;
+      pmd->process_mmaps()->AddVMRegion(region);

[Primiano Tucci (use gerrit), 2016/12/08 16:36:01]

ah you need also a call to 
pmd->set_has_process_mmaps(true)

+    }
+  }
+
+#endif
 #endif  // !defined(OS_IOS)
 
   pmd->process_totals()->set_resident_set_bytes(rss_bytes);