DevTools: [Timeline] Reset Memory Overview pane when clear button is clicked
DevTools: [Timeline] Reset Memory Overview pane when clear button is clicked

Contributed by pan.deng@intel.com

BUG=263683

Review URL: https://chromiumcodereview.appspot.com/20066005

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@154975 bbb929c8-8fbe-4397-9dbb-9b2b20218538

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