Add Wait* API to ActionRunner to wrap over WaitAction.

content/test/gpu/page_sets/gpu_process_tests.py

Index: content/test/gpu/page_sets/gpu_process_tests.py
diff --git a/content/test/gpu/page_sets/gpu_process_tests.py b/content/test/gpu/page_sets/gpu_process_tests.py
index c9abeb0c7c11d4e32a9d34e0b988c320840bca83..ee3ee478364c17eb03c460d062aad34eb94ab910 100644
--- a/content/test/gpu/page_sets/gpu_process_tests.py
+++ b/content/test/gpu/page_sets/gpu_process_tests.py
@@ -27,11 +27,8 @@ class FunctionalVideoPage(GpuProcessTestsPage):
 
   def RunNavigateSteps(self, action_runner):
     action_runner.NavigateToPage(self)
-    action_runner.RunAction(WaitAction(
-      {
-        'javascript': 'domAutomationController._finished',
-        'timeout': 30
-      }))
+    action_runner.WaitForJavaScriptCondition(
+        'domAutomationController._finished', timeout=30)
 
 
 class GpuProcessTestsPageSet(page_set_module.PageSet):