[Telemetry] Speed up page cycler by another ~20%.

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 e65865f55a8b8f7770ee4ae90b8b4d3cffa90731..a785ebb7ed730256750481e0885da82067533221 100644
--- a/tools/telemetry/telemetry/core/platform/android_platform_backend.py
+++ b/tools/telemetry/telemetry/core/platform/android_platform_backend.py
@@ -157,12 +157,12 @@ class AndroidPlatformBackend(
         break
     return child_pids
 
+  @decorators.Cache
   def GetCommandLine(self, pid):
-    ps = self._GetPsOutput(['pid', 'name'])
-    for curr_pid, curr_name in ps:
-      if int(curr_pid) == pid:
-        return curr_name
-    raise exceptions.ProcessGoneException()
+    ps = self._GetPsOutput(['pid', 'name'], pid)
+    if not ps:
+      raise exceptions.ProcessGoneException()
+    return ps[0][1]
 
   def GetOSName(self):
     return 'android'