webgl, cmaa: choose immutable texture instead of BGRA support for WebGL1

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 624 matching lines @@
         GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT3_EXT);
     validators_.texture_internal_format_storage.AddValue(
         GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT5_EXT);
   }
 
   // Note: Only APPLE_texture_format_BGRA8888 extension allows BGRA8_EXT in
   // ES3's glTexStorage2D, whereas EXT_texture_format_BGRA8888 doesn't provide
   // that compatibility. So if EXT_texture_format_BGRA8888 (but not
   // APPLE_texture_format_BGRA8888) is present on an underlying ES3 context, we
   // have to choose which one of BGRA vs texture storage we expose.
-  // When creating ES2 contexts, we prefer support BGRA to texture storage, so
-  // we disable texture storage if only EXT_texture_format_BGRA8888 is present.
+  // When creating ES2 contexts, we prefer support BGRA to texture storage, in
+  // order to use BGRA as platform color in the compositor, so we disable
+  // texture storage if only EXT_texture_format_BGRA8888 is present.
   // If neither is present, we expose texture storage.
   // When creating ES3 contexts, we do need to expose texture storage, so we
   // disable BGRA if we have to.
+  // When WebGL contexts, BRGA is not needed, because WebGL doesn't expose it.
   bool has_apple_bgra = extensions.Contains("GL_APPLE_texture_format_BGRA8888");
   bool has_ext_bgra = extensions.Contains("GL_EXT_texture_format_BGRA8888");
   bool enable_texture_format_bgra8888 =
       has_ext_bgra || has_apple_bgra || !gl_version_info_->is_es;
 
   bool has_ext_texture_storage = extensions.Contains("GL_EXT_texture_storage");
   bool has_arb_texture_storage = extensions.Contains("GL_ARB_texture_storage");
   bool has_texture_storage =
       !workarounds_.disable_texture_storage &&
       (has_ext_texture_storage || has_arb_texture_storage ||
        gl_version_info_->is_es3 || gl_version_info_->IsAtLeastGL(4, 2));
 
   bool enable_texture_storage = has_texture_storage;
 
   bool texture_storage_incompatible_with_bgra =
       gl_version_info_->is_es3 && !has_ext_texture_storage && !has_apple_bgra;
   if (texture_storage_incompatible_with_bgra &&
       enable_texture_format_bgra8888 && enable_texture_storage) {
     switch (context_type_) {
       case CONTEXT_TYPE_OPENGLES2:
-      case CONTEXT_TYPE_WEBGL1:
         enable_texture_storage = false;
         break;
       case CONTEXT_TYPE_OPENGLES3:
+      case CONTEXT_TYPE_WEBGL1:
       case CONTEXT_TYPE_WEBGL2:
         enable_texture_format_bgra8888 = false;
         break;
     }
   }
 
   if (enable_texture_format_bgra8888) {
     feature_flags_.ext_texture_format_bgra8888 = true;
     AddExtensionString("GL_EXT_texture_format_BGRA8888");
     validators_.texture_internal_format.AddValue(GL_BGRA_EXT);
@@ skipping 864 matching lines @@
   if (pos == std::string::npos) {
     extensions_ += (extensions_.empty() ? "" : " ") + str;
   }
 }
 
 FeatureInfo::~FeatureInfo() {
 }
 
 }  // namespace gles2
 }  // namespace gpu