[Telemetry] Rename PngBitmap->Bitmap and move it to core.

content/test/gpu/gpu_tests/pixel.py

 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 from datetime import datetime
 import glob
 import optparse
 import os
 import re
 
 from telemetry import test
-from telemetry.core.backends import png_bitmap
+from telemetry.core import bitmap
 from telemetry.page import page_test
 
 test_data_dir = os.path.abspath(os.path.join(
     os.path.dirname(__file__), '..', '..', 'data', 'gpu'))
 
 default_generated_data_dir = os.path.join(test_data_dir, 'generated')
 default_reference_image_dir = os.path.join(test_data_dir, 'gpu_reference')
 
 test_harness_script = r"""
   var domAutomationController = {};
@@ skipping 81 matching lines @@
     if not cur_revision:
       cur_revision = 0
 
     image_path = os.path.join(img_dir, img_name)
 
     PixelValidator.DeleteOldReferenceImages(image_path, cur_revision)
 
     image_path = image_path + '_' + str(cur_revision) + '.png'
 
     try:
-      ref_png = png_bitmap.PngBitmap.FromFile(image_path)
+      ref_png = bitmap.Bitmap.FromPngFile(image_path)
     except IOError:
       ref_png = None
 
     if ref_png:
       return ref_png
 
     print 'Reference image not found. Writing tab contents as reference.'
 
     PixelValidator.WriteImage(image_path, screenshot)
     return screenshot
@@ skipping 40 matching lines @@
     group.add_option('--build-revision',
         help='Chrome revision being tested.',
         default="unknownrev")
     parser.add_option_group(group)
 
   def CreatePageSet(self, options):
     page_set = super(Pixel, self).CreatePageSet(options)
     for page in page_set.pages:
       page.script_to_evaluate_on_commit = test_harness_script
     return page_set