[Telemetry] Fix idle wakeup reporting in the face of dead processes

tools/telemetry/telemetry/core/platform/mac_platform_backend.py

Index: tools/telemetry/telemetry/core/platform/mac_platform_backend.py
diff --git a/tools/telemetry/telemetry/core/platform/mac_platform_backend.py b/tools/telemetry/telemetry/core/platform/mac_platform_backend.py
index 1823483406064106f1870b2d00b8f1fdb1339b7d..d8fca578b3ebc69ee9b161d99a26fe5f8464b27d 100644
--- a/tools/telemetry/telemetry/core/platform/mac_platform_backend.py
+++ b/tools/telemetry/telemetry/core/platform/mac_platform_backend.py
@@ -9,6 +9,7 @@ import time
 from telemetry import decorators
 from telemetry.core.platform import platform_backend
 from telemetry.core.platform import posix_platform_backend
+from telemetry.core.platform import timeline_objects
 from telemetry.core.platform.power_monitor import powermetrics_power_monitor
 
 try:
@@ -46,10 +47,10 @@ class MacPlatformBackend(posix_platform_backend.PosixPlatformBackend):
     # Sometimes top won't return anything here, just ignore such cases -
     # crbug.com/354812 .
     if top_output[-2] != 'IDLEW':
-      return 0
+      return timeline_objects.IdleStatsData(pid, 0)
     # Numbers reported by top may have a '+' appended.
     wakeup_count = int(top_output[-1].strip('+ '))
-    return wakeup_count
+    return timeline_objects.IdleStatsData(pid, wakeup_count)
 
   def GetCpuStats(self, pid):
     """Return current cpu processing time of pid in seconds."""