Telemetry / Android: do not crash on GetCpuStats() if the process is gone.

tools/telemetry/telemetry/core/platform/android_platform_backend.py

Index: tools/telemetry/telemetry/core/platform/android_platform_backend.py
diff --git a/tools/telemetry/telemetry/core/platform/android_platform_backend.py b/tools/telemetry/telemetry/core/platform/android_platform_backend.py
index 9097dadd9e017024876399b86156098677fa7313..69ddfde8ee8c14eb27b078806a7dd2cf08ebb767 100644
--- a/tools/telemetry/telemetry/core/platform/android_platform_backend.py
+++ b/tools/telemetry/telemetry/core/platform/android_platform_backend.py
@@ -86,8 +86,11 @@ class AndroidPlatformBackend(platform_backend.PlatformBackend):
       logging.warning('CPU stats cannot be retrieved on non-rooted device.')
       return {}
     stats = self._adb.GetProtectedFileContents('/proc/%s/stat' % pid,
-                                               log_result=False)[0].split()
-    return proc_util.GetCpuStats(stats)
+                                               log_result=False)
+    if not stats:
+      logging.warning('Unable to get /proc/%s/stat, process gone?', pid)
+      return {}
+    return proc_util.GetCpuStats(stats[0].split())
 
   def GetCpuTimestamp(self):
     if not self._adb.CanAccessProtectedFileContents():