Implement WEBGL_compressed_texture_es3_0 extension for WebGL 1/2

gpu/command_buffer/service/feature_info.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "gpu/command_buffer/service/feature_info.h"
 
 #include <stddef.h>
 
 #include <set>
 #include <vector>
@@ skipping 994 matching lines @@
     validators_.g_l_state.AddValue(GL_TEXTURE_BINDING_EXTERNAL_OES);
   }
 
   if (extensions.Contains("GL_OES_compressed_ETC1_RGB8_texture")) {
     AddExtensionString("GL_OES_compressed_ETC1_RGB8_texture");
     feature_flags_.oes_compressed_etc1_rgb8_texture = true;
     validators_.compressed_texture_format.AddValue(GL_ETC1_RGB8_OES);
     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_.compressed_texture_format.AddValue(
+        GL_COMPRESSED_R11_EAC);

[Ken Russell (switch to Gerrit), 2016/09/21 00:16:07]

I think we need to be careful about whether these values have already been
added. If the context type is WebGL 2.0 or ES 3.0 then
FeatureInfo::EnableES3Validators will add these. See its call in
GLES2DecoderImpl::Initialize.

Let's refactor this code and add a
FeatureInfo::EnableES3CompressedTextureFormats to avoid duplicating code. Could
you modify src/gpu/command_buffer/build_gles2_cmd_buffer.py and have it generate
a Validators::UpdateES3CompressedTextureFormats which is called by
Validators::UpdateValuesES3?

+    validators_.compressed_texture_format.AddValue(
+        GL_COMPRESSED_SIGNED_R11_EAC);
+    validators_.compressed_texture_format.AddValue(
+        GL_COMPRESSED_RGB8_ETC2);
+    validators_.compressed_texture_format.AddValue(
+        GL_COMPRESSED_SRGB8_ETC2);
+    validators_.compressed_texture_format.AddValue(
+        GL_COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2);
+    validators_.compressed_texture_format.AddValue(
+        GL_COMPRESSED_SRGB8_PUNCHTHROUGH_ALPHA1_ETC2);
+    validators_.compressed_texture_format.AddValue(
+        GL_COMPRESSED_RG11_EAC);
+    validators_.compressed_texture_format.AddValue(
+        GL_COMPRESSED_SIGNED_RG11_EAC);
+    validators_.compressed_texture_format.AddValue(
+        GL_COMPRESSED_RGBA8_ETC2_EAC);
+    validators_.compressed_texture_format.AddValue(
+        GL_COMPRESSED_SRGB8_ALPHA8_ETC2_EAC);
+
+    validators_.texture_internal_format_storage.AddValue(
+        GL_COMPRESSED_R11_EAC);
+    validators_.texture_internal_format_storage.AddValue(
+        GL_COMPRESSED_SIGNED_R11_EAC);
+    validators_.texture_internal_format_storage.AddValue(
+        GL_COMPRESSED_RGB8_ETC2);
+    validators_.texture_internal_format_storage.AddValue(
+        GL_COMPRESSED_SRGB8_ETC2);
+    validators_.texture_internal_format_storage.AddValue(
+        GL_COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2);
+    validators_.texture_internal_format_storage.AddValue(
+        GL_COMPRESSED_SRGB8_PUNCHTHROUGH_ALPHA1_ETC2);
+    validators_.texture_internal_format_storage.AddValue(
+        GL_COMPRESSED_RG11_EAC);
+    validators_.texture_internal_format_storage.AddValue(
+        GL_COMPRESSED_SIGNED_RG11_EAC);
+    validators_.texture_internal_format_storage.AddValue(
+        GL_COMPRESSED_RGBA8_ETC2_EAC);
+    validators_.texture_internal_format_storage.AddValue(
+        GL_COMPRESSED_SRGB8_ALPHA8_ETC2_EAC);
+  }
+
   if (extensions.Contains("GL_AMD_compressed_ATC_texture")) {
     AddExtensionString("GL_AMD_compressed_ATC_texture");
     validators_.compressed_texture_format.AddValue(
         GL_ATC_RGB_AMD);
     validators_.compressed_texture_format.AddValue(
         GL_ATC_RGBA_EXPLICIT_ALPHA_AMD);
     validators_.compressed_texture_format.AddValue(
         GL_ATC_RGBA_INTERPOLATED_ALPHA_AMD);
 
     validators_.texture_internal_format_storage.AddValue(
@@ skipping 506 matching lines @@
   if (pos == std::string::npos) {
     extensions_ += (extensions_.empty() ? "" : " ") + str;
   }
 }
 
 FeatureInfo::~FeatureInfo() {
 }
 
 }  // namespace gles2
 }  // namespace gpu