Make credential_path a page attribute instead of page_set attribute.

tools/telemetry/telemetry/unittest/page_set_smoke_test.py

Index: tools/telemetry/telemetry/unittest/page_set_smoke_test.py
diff --git a/tools/telemetry/telemetry/unittest/page_set_smoke_test.py b/tools/telemetry/telemetry/unittest/page_set_smoke_test.py
index bfe86e08f6bc6ba9f0dd2d654128c47fe8af5403..83ab529c9973774e75b4abe71d43e558f2d319b9 100644
--- a/tools/telemetry/telemetry/unittest/page_set_smoke_test.py
+++ b/tools/telemetry/telemetry/unittest/page_set_smoke_test.py
@@ -10,6 +10,7 @@ from telemetry.core import browser_credentials
 from telemetry.core import discover
 from telemetry.page import page_set as page_set_module
 from telemetry.page import page_set_archive_info
+from telemetry.util import classes
 
 
 class PageSetSmokeTest(unittest.TestCase):
@@ -40,11 +41,11 @@ class PageSetSmokeTest(unittest.TestCase):
 
   def CheckCredentials(self, page_set):
     """Verify that all pages in page_set use proper credentials"""
-    credentials = browser_credentials.BrowserCredentials()
-    if page_set.credentials_path:
-      credentials.credentials_path = (
-          os.path.join(page_set.base_dir, page_set.credentials_path))
     for page in page_set.pages:
+      credentials = browser_credentials.BrowserCredentials()
+      if page.credentials_path:
+        credentials.credentials_path = (
+            os.path.join(page.base_dir, page.credentials_path))
       fail_message = ('page %s of %s has invalid credentials %s' %
                       (page.url, page_set.file_path, page.credentials))
       if page.credentials:
@@ -108,6 +109,8 @@ class PageSetSmokeTest(unittest.TestCase):
       try:
         page_set = page_set_class()
       except TypeError:

[dtu, 2014/10/06 21:30:22]

What is this except block for in the first place? I just ran perf and gpu unit
tests without it, and they still pass.

[nednguyen, 2014/10/07 20:11:09]

There are some page_set that aren't directly constructable in perf/internal. I
guess Tony added this except to ignore them all. 
However, when I remove credentials_path argument from PageSet.__init__, this try
catch block make this test still pass even if I don't remove the
crendentials_path call in super(PageSetX, self).__init__(...)

[dtu, 2014/10/08 21:34:18]

Interesting, okay.

+        if classes.IsDirectlyConstructable(page_set_class):
+          raise
         continue
       logging.info('Testing %s', page_set.file_path)
       self.CheckArchive(page_set)