Include browser type in GPU Gold parameters

Includes the browser type reported by Telemetry in the Gold parameters
used by the GPU tests. This will help with identifying cases where two
different browsers on the same hardware are producing different results,
e.g. Chrome and Webview on Android devices.

Change-Id: Ib7c566dcd751a0e3b23df9583a034952657f2471
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2630285Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Commit-Queue: Brian Sheedy <bsheedy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#843779}

content/test/gpu/gpu_tests/skia_gold_integration_test_base.py

@@ -314,6 +314,8 @@ class SkiaGoldIntegrationTestBase(gpu_integration_test.GpuIntegrationTest):
         _ToNonEmptyStrOrNone(img_params.driver_vendor),
         'combined_hardware_identifier':
         _GetCombinedHardwareIdentifier(img_params),
+        'browser_type':
+        _ToNonEmptyStrOrNone(self.browser.browser_type),
     }
     # If we have a grace period active, then the test is potentially flaky.
     # Include a pair that will cause Gold to ignore any untriaged images, which