[Fuchsia] Enable OOP UI raster by default

This is no-op: we don't have any chrome UI on Fuchsia, but we will
want to use OOP when any UI is added.

Bug: 962617
Change-Id: I9aea13556e2c49101f15d1935f465de353964c9f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1611220Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#659471}

ui/base/ui_base_features.cc

@@ -45,7 +45,7 @@ bool IsNotificationIndicatorEnabled() {
 
 // Enables GPU rasterization for all UI drawing (where not blacklisted).
 const base::Feature kUiGpuRasterization = {"UiGpuRasterization",
-#if defined(OS_MACOSX) || defined(OS_CHROMEOS)
+#if defined(OS_MACOSX) || defined(OS_CHROMEOS) || defined(OS_FUCHSIA)
                                            base::FEATURE_ENABLED_BY_DEFAULT
 #else
                                            base::FEATURE_DISABLED_BY_DEFAULT