gpu testing: Handle non-integral device pixel ratio.

content/test/gpu/gpu_tests/gpu_rasterization.py

 # Copyright 2014 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.
 
 import optparse
 import cloud_storage_test_base
 
 test_harness_script = r"""
   var domAutomationController = {};
   domAutomationController._succeeded = false;
@@ skipping 31 matching lines @@
 
     if not tab.screenshot_supported:
       raise page_test.Failure('Browser does not support screenshot capture')
 
     screenshot = tab.Screenshot()
     if not screenshot:
       raise page_test.Failure('Could not capture screenshot')
 
     device_pixel_ratio = tab.EvaluateJavaScript('window.devicePixelRatio')
     if hasattr(page, 'test_rect'):
-      test_rect = [x * device_pixel_ratio for x in page.test_rect]
+      test_rect = [int(x * device_pixel_ratio) for x in page.test_rect]
       screenshot = screenshot.Crop(
           test_rect[0], test_rect[1],
           test_rect[2], test_rect[3])
 
     self._ValidateScreenshotSamples(
         page.display_name,
         screenshot,
         page.expectations,
         device_pixel_ratio)
 
 
 class GpuRasterization(cloud_storage_test_base.TestBase):
   """Tests that GPU rasterization produces valid content"""
   test = _GpuRasterizationValidator
   page_set = 'page_sets/gpu_rasterization_tests.py'
 
   def CreatePageSet(self, options):
     page_set = super(GpuRasterization, self).CreatePageSet(options)
     for page in page_set.pages:
       page.script_to_evaluate_on_commit = test_harness_script
     return page_set