viz: Enable SkiaRenderer layout test

To run layout test over SkiaRenderer, need to add flag --additional-driver-flag=--use-skia-renderer.

BUG=820356

Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel
Change-Id: Ic289b19cda9cfcb96bf38217eb20b890bb808f5a
Reviewed-on: https://chromium-review.googlesource.com/1001872Reviewed-by: weiliangc <weiliangc@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Xing Xu <xing.xu@intel.com>
Cr-Commit-Position: refs/heads/master@{#549539}

content/browser/renderer_host/render_process_host_impl.cc

@@ -2755,6 +2755,7 @@ void RenderProcessHostImpl::PropagateBrowserCommandLineToRenderer(
     switches::kUseGL,
     switches::kUseGpuInTests,
     switches::kUseMobileUserAgent,
+    switches::kUseSkiaRenderer,
     switches::kV,
     switches::kVideoThreads,
     switches::kVideoUnderflowThresholdMs,

content/test/layouttest_support.cc

@@ -54,6 +54,7 @@
 #include "third_party/blink/public/platform/web_input_event.h"
 #include "third_party/blink/public/platform/web_rect.h"
 #include "third_party/blink/public/web/web_view.h"
+#include "ui/base/ui_base_switches.h"
 #include "ui/events/blink/blink_event_util.h"
 #include "ui/gfx/geometry/vector2d.h"
 #include "ui/gfx/icc_profile.h"
@@ -336,6 +337,8 @@ class LayoutTestDependenciesImpl : public LayoutTestDependencies,
     // Keep texture sizes exactly matching the bounds of the RenderPass to avoid
     // floating point badness in texcoords.
     renderer_settings.dont_round_texture_sizes_for_pixel_tests = true;
+    renderer_settings.use_skia_renderer =
+        cmd->HasSwitch(switches::kUseSkiaRenderer);
 
     constexpr bool disable_display_vsync = false;
     constexpr double refresh_rate = 60.0;