Add trivial animation page to trivial_sites perf benchmark.

tools/perf/page_sets/trivial_sites.py

Index: tools/perf/page_sets/trivial_sites.py
diff --git a/tools/perf/page_sets/trivial_sites.py b/tools/perf/page_sets/trivial_sites.py
index c0bd865ddf23167f62bdf9af929b5c91f82cad45..ae951d74177e89474a229560cef6358beb3db3f4 100644
--- a/tools/perf/page_sets/trivial_sites.py
+++ b/tools/perf/page_sets/trivial_sites.py
@@ -118,6 +118,19 @@ class TrivialGifPage(_BasePage):
         measure_memory=measure_memory)
 
 
+class TrivialAnimationPage(_BasePage):
+
+  def __init__(self, page_set, shared_page_state_class, wait_in_seconds,
+               measure_memory):
+    super(TrivialAnimationPage, self).__init__(
+        url='file://trivial_sites/trivial_animation.html',
+        page_set=page_set,
+        name=self.__class__.__name__ + shared_page_state_class.__name__,
+        shared_page_state_class=shared_page_state_class,
+        wait_in_seconds=wait_in_seconds,
+        measure_memory=measure_memory)
+
+
 class TrivialSitesStorySet(story.StorySet):
   def __init__(self, shared_state = shared_page_state.SharedPageState,
                wait_in_seconds=0, measure_memory=False):
@@ -138,3 +151,5 @@ class TrivialSitesStorySet(story.StorySet):
         self, shared_state, wait_in_seconds, measure_memory))
     self.AddStory(TrivialGifPage(
         self, shared_state, wait_in_seconds, measure_memory))
+    self.AddStory(TrivialAnimationPage(
+        self, shared_state, wait_in_seconds, measure_memory))