How to show total memory used by a process AND ALL its children

Just want to see if there is any particular process gobbling up memory. E.g. chrome has a whole tree of chrome processes: $ pstree 20679 chrome─┬─2*[cat] ├─chrome─┬─chrome─┬─chrome───15*[{chrome}] │ │ ├─12*[chrome───10*[{chrome}]] │ │ ├─18*[chrome───12*[{chrome}]] │ │ ├─2*[chrome───11*[{chrome}]] │ │ ├─chrome───9*[{chrome}] │ │ ├─chrome───14*[{chrome}] │ │ └─4*[chrome───13*[{chrome}]] │ └─nacl_helper ├─chrome─┬─chrome │ └─5*[{chrome}] ├─chrome───9*[{chrome}] └─31*[{chrome}] How do I…

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