Telemetry: featurize tab_switching test for compressed swap performance

tools/telemetry/telemetry/core/util.py

Index: tools/telemetry/telemetry/core/util.py
diff --git a/tools/telemetry/telemetry/core/util.py b/tools/telemetry/telemetry/core/util.py
index 460eb61ec7fb42bd131ac891b96af6769eaaeef3..5d666e4318ccc536261bbdaa2910c2501e607279 100644
--- a/tools/telemetry/telemetry/core/util.py
+++ b/tools/telemetry/telemetry/core/util.py
@@ -50,10 +50,11 @@ def GetPythonPageSetModule(file_path):
   return imp.load_source(_GetUniqueModuleName(), file_path)
 
 
-def WaitFor(condition, timeout):
+def WaitFor(condition, timeout, fixed_poll_interval=None):
   """Waits for up to |timeout| secs for the function |condition| to return True.
 
-  Polling frequency is (elapsed_time / 10), with a min of .1s and max of 5s.
+  Polling interval is (elapsed_time / 10), with a min of .1s and max of 5s,
+  unless |fixed_poll_interval| is specified.
 
   Returns:
     Result of |condition| function (if present).
@@ -86,7 +87,8 @@ def WaitFor(condition, timeout):
       logging.info('Continuing to wait %ds for %s. Elapsed: %ds.',
                    timeout, GetConditionString(), elapsed_time)
       last_output_time = time.time()
-    poll_interval = min(max(elapsed_time / 10., min_poll_interval),
+    poll_interval = fixed_poll_interval or \
+                    min(max(elapsed_time / 10., min_poll_interval),
                         max_poll_interval)
     time.sleep(poll_interval)