Implement WEBGL_compressed_texture_es3_0 extension for WebGL 1/2

gpu/command_buffer/service/feature_info.cc

Index: gpu/command_buffer/service/feature_info.cc
diff --git a/gpu/command_buffer/service/feature_info.cc b/gpu/command_buffer/service/feature_info.cc
index d19c308e661fc8e1779eb3c8bf59d317ab49f99f..b177e98530aff5510c21e61aabd93af080bf9c74 100644
--- a/gpu/command_buffer/service/feature_info.cc
+++ b/gpu/command_buffer/service/feature_info.cc
@@ -1012,6 +1012,13 @@ void FeatureInfo::InitializeFeatures() {
     validators_.texture_internal_format_storage.AddValue(GL_ETC1_RGB8_OES);
   }
 
+  // TODO(kainino): Once we have a way to query whether ANGLE is exposing
+  // native support for ETC2 textures, require that here.
+  if (gl_version_info_->is_es3) {
+    AddExtensionString("GL_CHROMIUM_compressed_texture_es3_0");
+    validators_.UpdateES30CompressedTextureFormats();
+  }
+
   if (extensions.Contains("GL_AMD_compressed_ATC_texture")) {
     AddExtensionString("GL_AMD_compressed_ATC_texture");
     validators_.compressed_texture_format.AddValue(