aw: Add UseGles2ForOopR to DEV_UI

This CL adds UseGles2ForOopR to devui to help debug issues that might
be related to this feature.

Change-Id: I171d4c61d2269b83969d1aab0f1140a857f53a26
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2490989Reviewed-by: Bo <boliu@chromium.org>
Commit-Queue: Vasiliy Telezhnikov <vasilyt@chromium.org>
Cr-Commit-Position: refs/heads/master@{#819924}

android_webview/java/src/org/chromium/android_webview/common/ProductionSupportedFlagList.java

@@ -70,6 +70,8 @@ public final class ProductionSupportedFlagList {
             Flag.baseFeature(GpuFeatures.ENABLE_SHARED_IMAGE_FOR_WEBVIEW,
                     "Enables shared images for WebView."),
             Flag.baseFeature(VizFeatures.VIZ_FOR_WEBVIEW, "Enables Viz for WebView."),
+            Flag.baseFeature(
+                    GpuFeatures.USE_GLES2_FOR_OOP_R, "Force Skia context to use es2 only."),
             Flag.baseFeature(AwFeatures.WEBVIEW_CONNECTIONLESS_SAFE_BROWSING,
                     "Uses GooglePlayService's 'connectionless' APIs for Safe Browsing "
                             + "security checks."),