Add Pixel 2 pixel ratio override

Adds a pixel ratio override for Pixel 2 devices in the GPU pixel tests.
The ratio reported by the device was larger than it should be, causing
the tests to compare larger portions of the image than it should.

Bug: 966069
Change-Id: Ic1ec2d65762170d5f62f4570cff6e96ac2aa0f6a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1627916Reviewed-by: Kenneth Russell <kbr@chromium.org>
Commit-Queue: Brian Sheedy <bsheedy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#663167}

content/test/gpu/gpu_tests/pixel_test_pages.py

@@ -118,6 +118,10 @@ SCALE_FACTOR_OVERRIDES = {
       "comment": "NVIDIA Shield",
       "device_type": "sb_na_wf",
       "scale_factor": 1.226
+    },
+    {
+      "device_type": "Pixel 2",
+      "scale_factor": 1.1067
     }
   ]
 }