Don't expose EXT_color_buffer_half_float to GL 2.x

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 1488 matching lines @@
       };
       DCHECK_EQ(arraysize(internal_formats), arraysize(formats));
       for (size_t i = 0; i < arraysize(formats); ++i) {
         glTexImage2D(GL_TEXTURE_2D, 0, internal_formats[i], width, width, 0,
                      formats[i], GL_FLOAT, NULL);
         full_float_support &= glCheckFramebufferStatusEXT(GL_FRAMEBUFFER) ==
                               GL_FRAMEBUFFER_COMPLETE;
       }
       enable_ext_color_buffer_float = full_float_support;
     }
-    // Likewise for EXT_color_buffer_half_float on ES2 contexts.
-    if (IsWebGL1OrES2Context() && !enable_ext_color_buffer_half_float) {
+    // Likewise for EXT_color_buffer_half_float on ES2 contexts. On desktop,
+    // require at least GL 3.0, to ensure that all formats are defined (ES
+    // queries the extension directly).
+    if (IsWebGL1OrES2Context() && !enable_ext_color_buffer_half_float &&
+        gl_version_info_->IsAtLeastGL(3, 0)) {

[Zhenyao Mo, 2017/05/04 22:07:23]

Sorry, just realized this.  gl_version_info_->IsAtLeastGL(3, 0) will return
false on ES.  I think it should be
(gl_version_info_->is_es || gl_version_info_->IsAtLeastGL(3, 0))

[ccameron, 2017/05/04 22:18:27]

I think there is an implicit gl_version_info_->is_es in this .. but yeah, let's
make it explicit.

       bool full_half_float_support = true;
       GLenum internal_formats[] = {
           GL_R16F, GL_RG16F, GL_RGBA16F,
       };
       GLenum formats[] = {
           GL_RED, GL_RG, GL_RGBA,
       };
       GLenum data_type = GL_FLOAT;
       if (gl_version_info_->is_es2)
         data_type = GL_HALF_FLOAT_OES;
@@ skipping 175 matching lines @@
   if (pos == std::string::npos) {
     extensions_ += (extensions_.empty() ? "" : " ") + str;
   }
 }
 
 FeatureInfo::~FeatureInfo() {
 }
 
 }  // namespace gles2
 }  // namespace gpu