Add readback path for CopyTextureCHROMIUM

gpu/command_buffer/service/gles2_cmd_decoder.cc

Index: gpu/command_buffer/service/gles2_cmd_decoder.cc
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder.cc b/gpu/command_buffer/service/gles2_cmd_decoder.cc
index 6fb3faedb45e9143ac7acb69278d480f448bd20b..7b8d03e244c4fbccc718607b161aa362acb39b25 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -16482,8 +16482,6 @@ bool GLES2DecoderImpl::ValidateCopyTextureCHROMIUMInternalFormats(
       valid_dest_format = feature_info_->IsWebGL2OrES3Context();
       break;
     case GL_RGB9_E5:
-      valid_dest_format = !gl_version_info().is_es;
-      break;
     case GL_R16F:
     case GL_R32F:
     case GL_RG16F:
@@ -16554,6 +16552,32 @@ CopyTextureMethod GLES2DecoderImpl::getCopyTextureCHROMIUMMethod(
       Texture::ColorRenderable(GetFeatureInfo(), dest_internal_format, false);
   std::string output_error_msg;
 
+  switch (dest_internal_format) {
+#if defined(OS_MACOSX)

[Zhenyao Mo, 2017/03/20 17:05:40]

Can we hook this up with a driver bug workaround so we only limit it to NVidia
on OSX?

[qiankun, 2017/03/21 08:47:13]

I can do this.

[qiankun, 2017/03/29 09:00:10]

I added the workaround for NVIDIA Mac. But it didn't detect correct driver
vendor on a bot with two GPUs (Intel + NVIDIA). I will try it in a standalone CL
after this CL is merged..

+    // RGB5_A1 is not color-renderable on NVIDIA Mac, see crbug.com/676209.
+    case GL_RGB5_A1:
+      return DRAW_AND_READBACK;
+#endif
+    // RGB9_E5 isn't accepted by glCopyTexImage2D if underlying context is ES.
+    case GL_RGB9_E5:
+      if (gl_version_info().is_es)
+        return DRAW_AND_READBACK;
+      break;
+    // SRGB format has color-space conversion issue, see
+    // https://github.com/KhronosGroup/WebGL/issues/2165.
+    // TODO(qiankun.miao@intel.com): revisit this once the above issue is
+    // resolved.

[Zhenyao Mo, 2017/03/20 17:05:40]

Can we not put them on DRAW_AND_READBACK path for now? So at least the
performance will be good.

[qiankun, 2017/03/21 08:47:13]

We cannot detect internalformat in texSubImage2D in Blink. So, it's impossible
to filter SRGB subImage uploading unless we disable CopyTextureCHROMIUM for all
format/type combinations when doing texSubImage2D.

[qiankun, 2017/03/22 02:52:30]

I put SRGB related formats here because current GPU-GPU copy for copying RGBA
texture to SRGB texture does linear-to-srgb color space conversion. But, tThis
conversion isn't done in current CPU uploading path in Blink. Current CTS tests
doesn't expect the color space conversion either. So, I did a fallback path for
thest SRGB formats. Are we talking about this?

+    case GL_SRGB_EXT:
+    case GL_SRGB_ALPHA_EXT:
+    case GL_SRGB8:
+    case GL_SRGB8_ALPHA8:
+      if (feature_info_->IsWebGLContext())
+        return DRAW_AND_READBACK;
+      break;
+    default:
+      break;
+  }
+
   // CopyTexImage* should not allow internalformat of GL_BGRA_EXT and
   // GL_BGRA8_EXT. crbug.com/663086.
   bool copy_tex_image_format_valid =