16-bit video upload to float: intermediate R16_EXT and copy to float.

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 32e72c69f32652768c47c267509af2b3df97b8d9..14be4fd1628f63a875ec6bf458fbeed63d6f0531 100644
--- a/gpu/command_buffer/service/feature_info.cc
+++ b/gpu/command_buffer/service/feature_info.cc
@@ -1293,6 +1293,19 @@ void FeatureInfo::InitializeFeatures() {
   }
   UMA_HISTOGRAM_BOOLEAN("GPU.TextureRG", feature_flags_.ext_texture_rg);
 
+  if (gl_version_info_->is_desktop_core_profile ||
+      extensions.Contains("GL_EXT_texture_norm16")) {
+    feature_flags_.ext_texture_norm16 = true;
+    AddExtensionString("GL_EXT_texture_norm16");
+
+    // Note: EXT_texture_norm16 is not exposed through WebGL API so we validate
+    // only the combinations used internally.
+    validators_.texture_format.AddValue(GL_RED_EXT);
+    validators_.texture_internal_format.AddValue(GL_R16_EXT);
+    validators_.texture_internal_format.AddValue(GL_RED_EXT);
+    validators_.texture_unsized_internal_format.AddValue(GL_RED_EXT);

[Ken Russell (switch to Gerrit), 2017/04/20 01:47:06]

Have you confirmed that these aren't accessible when calling through the WebGL
API? I'm pretty sure that WebGL2RenderingContextBase should catch attempts to
use them.

Could you add a WebGL conformance test under conformance2/textures/misc/ that
tries to allocate textures with these internal formats, and confirms that the
attempts fail?

We also need to make sure that we can't now suddenly allocate unsized GL_RED
textures from WebGL, if GL_R8 is the only legally supported internal format from
the ES3 standpoint.

[aleksandar.stojiljkovic, 2017/04/26 13:29:40]

Thanks.
Done.
https://github.com/KhronosGroup/WebGL/pull/2379

+  }
+
   bool has_opengl_dual_source_blending =
       gl_version_info_->IsAtLeastGL(3, 3) ||
       (gl_version_info_->IsAtLeastGL(3, 2) &&