telemetry: Allow page tests to be configured via constructor

tools/perf/measurements/skpicture_printer.py

Index: tools/perf/measurements/skpicture_printer.py
diff --git a/tools/perf/measurements/skpicture_printer.py b/tools/perf/measurements/skpicture_printer.py
index 687cf0cd4d7caa1cc73c5b7bdd7337ffa115ad06..5ac9462ce090dc00410e5e1b9bdaed00a972a754 100644
--- a/tools/perf/measurements/skpicture_printer.py
+++ b/tools/perf/measurements/skpicture_printer.py
@@ -12,16 +12,18 @@ _JS = 'chrome.gpuBenchmarking.printToSkPicture("{0}");'
 
 
 class SkpicturePrinter(page_test.PageTest):
-  @classmethod
-  def AddCommandLineArgs(cls, parser):
+  def __init__(self):
+    super(SkpicturePrinter, self).__init__()
+    self._skp_outdir = None
+
+  def AddCommandLineArgs(self, parser):
     parser.add_option('-s', '--skp-outdir',
                       help='Output directory for the SKP files')
 
-  @classmethod
-  def ProcessCommandLineArgs(cls, parser, args):
+  def ProcessCommandLineArgs(self, parser, args):
     if not args.skp_outdir:
       parser.error('Please specify --skp-outdir')
-    cls._skp_outdir = args.skp_outdir
+    self._skp_outdir = args.skp_outdir
 
   def CustomizeBrowserOptions(self, options):
     options.AppendExtraBrowserArgs(['--enable-gpu-benchmarking',