[telemetry] Clean up image decoding benchmark

tools/telemetry/telemetry/page_test.py

Index: tools/telemetry/telemetry/page_test.py
diff --git a/tools/telemetry/telemetry/page_test.py b/tools/telemetry/telemetry/page_test.py
index 0aaf2304966a9beed44f73836b0801596f1a2d95..eb4938f20a50a92a5ab6431c46b80848497d8fda 100644
--- a/tools/telemetry/telemetry/page_test.py
+++ b/tools/telemetry/telemetry/page_test.py
@@ -65,6 +65,15 @@ class PageTest(object):
     """Override to customize if the test can be ran for the given page."""
     return True
 
+  def WillNavigateToPage(self, page, tab):
+    """Override to do operations before the page is navigated."""
+    pass
+
+  def DidNavigateToPage(self, page, tab):
+    """Override to do operations right after the page is navigated, but before
+    any waiting for completion has occurred."""
+    pass
+
   def WillRunInteraction(self, page, tab):
     """Override to do operations before running the interaction on the page."""
     pass