Don't expose EXT_color_buffer_half_float to GL 2.x

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 14be4fd1628f63a875ec6bf458fbeed63d6f0531..e7c85f9e3e2c63c6b67922afc3750165b94f069d 100644
--- a/gpu/command_buffer/service/feature_info.cc
+++ b/gpu/command_buffer/service/feature_info.cc
@@ -1506,8 +1506,11 @@ void FeatureInfo::InitializeFloatAndHalfFloatFeatures(
       }
       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,