Updates exception and adds rety to ExecuteAsyncJavaScript

chrome/test/media_router/telemetry/benchmarks/pagesets/media_router_perf_pages.py

Index: chrome/test/media_router/telemetry/benchmarks/pagesets/media_router_perf_pages.py
diff --git a/chrome/test/media_router/telemetry/benchmarks/pagesets/media_router_perf_pages.py b/chrome/test/media_router/telemetry/benchmarks/pagesets/media_router_perf_pages.py
index 701a1b30a6e09421557e8c8f2d9941c3c7d44e2c..f15f85674c2b6daca37af5800ed08d06a2c0f190 100644
--- a/chrome/test/media_router/telemetry/benchmarks/pagesets/media_router_perf_pages.py
+++ b/chrome/test/media_router/telemetry/benchmarks/pagesets/media_router_perf_pages.py
@@ -125,7 +125,7 @@ class CastFlingingPage(media_router_page.CastPage):
           'stopSession();',
           lambda: not action_runner.EvaluateJavaScript('currentSession'),
           'Failed to stop session',
-          timeout=30)
+          timeout=60, retry=3)
 
 
 class CastMirroringPage(media_router_page.CastPage):
@@ -169,7 +169,7 @@ class CastMirroringPage(media_router_page.CastPage):
         if tab.url == 'chrome://media-router/':
           self.WaitUntilDialogLoaded(action_runner, tab)
           if not self.CheckIfExistingRoute(tab, sink_name):
-            raise page.page_test.Failure('Failed to start mirroring session.')
+            raise RuntimeError('Failed to start mirroring session.')
       action_runner.ExecuteJavaScript('collectPerfData();')
       action_runner.Wait(SESSION_TIME)
       self.CloseExistingRoute(action_runner, sink_name)