[Telemetry] Add a page set option to use all cold page loads.

tools/telemetry/telemetry/page/page_test.py

Index: tools/telemetry/telemetry/page/page_test.py
diff --git a/tools/telemetry/telemetry/page/page_test.py b/tools/telemetry/telemetry/page/page_test.py
index fbc4c63690265e055eebfdbf55d453fd32c5fd1e..12f227f7879cfe6fec25cb0927225efbfe8e54de 100644
--- a/tools/telemetry/telemetry/page/page_test.py
+++ b/tools/telemetry/telemetry/page/page_test.py
@@ -49,7 +49,8 @@ class PageTest(object):
                test_method_name,
                action_name_to_run='',
                needs_browser_restart_after_each_run=False,
-               discard_first_result=False):
+               discard_first_result=False,
+               clear_cache_before_each_run=False):
     self.options = None
     try:
       self._test_method = getattr(self, test_method_name)
@@ -60,6 +61,7 @@ class PageTest(object):
     self._needs_browser_restart_after_each_run = (
         needs_browser_restart_after_each_run)
     self._discard_first_result = discard_first_result
+    self._clear_cache_before_each_run = clear_cache_before_each_run
 
   @property
   def discard_first_result(self):
@@ -68,6 +70,12 @@ class PageTest(object):
     the first run of the test can warm things up. """
     return self._discard_first_result
 
+  @property
+  def clear_cache_before_each_run(self):
+    """When set to True, the browser's disk and memory cache will be cleared
+    before each run."""
+    return self._clear_cache_before_each_run
+
   def NeedsBrowserRestartAfterEachRun(self, tab): # pylint: disable=W0613
     """Override to specify browser restart after each run."""
     return self._needs_browser_restart_after_each_run