[Tentaive patch for discussion] Add Purge+Suspend metrics as UMA.

tools/perf/page_sets/blink_memory_mobile.py

Index: tools/perf/page_sets/blink_memory_mobile.py
diff --git a/tools/perf/page_sets/blink_memory_mobile.py b/tools/perf/page_sets/blink_memory_mobile.py
index 3c38d9e627f304807a8ca73fdf0b4af8324a4719..dbb5ce99c161865a6638cc77aee4dcaa703d45a5 100644
--- a/tools/perf/page_sets/blink_memory_mobile.py
+++ b/tools/perf/page_sets/blink_memory_mobile.py
@@ -25,8 +25,14 @@ class BlinkMemoryMobilePage(page_module.Page):
   def _DumpMemory(self, action_runner, phase):
     with action_runner.CreateInteraction(phase):
       action_runner.Wait(DUMP_WAIT_TIME)
+      # Open blank tab (Move the page to background).
+      action_runner.tab.browser.tabs.New()
+      action_runner.Wait(5)
       action_runner.ForceGarbageCollection()
-      action_runner.SimulateMemoryPressureNotification('critical')
+      if not action_runner.tab.browser.DumpMemory():
+        logging.error('Unable to get a memory dump for %s.', self.name)
+      action_runner.Wait(20)
+      #action_runner.SimulateMemoryPressureNotification('critical')
       action_runner.Wait(DUMP_WAIT_TIME)
       if not action_runner.tab.browser.DumpMemory():
         logging.error('Unable to get a memory dump for %s.', self.name)