tracing: Add private footprint

tracing/tracing/model/process_memory_dump.html

Index: tracing/tracing/model/process_memory_dump.html
diff --git a/tracing/tracing/model/process_memory_dump.html b/tracing/tracing/model/process_memory_dump.html
index a284d33d37f3c66a5df700918d1fa637366e29b8..064141c3db7680e86e8fec610a0d1dddcf6dcdbf 100644
--- a/tracing/tracing/model/process_memory_dump.html
+++ b/tracing/tracing/model/process_memory_dump.html
@@ -50,6 +50,7 @@ tr.exportTo('tr.model', function() {
     //   - peakResidentBytes: Peak resident bytes (number)
     //   - arePeakResidentBytesResettable: Flag whether peak resident bytes are
     //     resettable (boolean)
+    //   - privateFootprintBytes: Private footprint bytes (number)
     //   - platformSpecific: Map from OS-specific total names (string) to sizes
     //     (number)
     this.totals = undefined;