gpu: Expose internal format R8 instead of RED.

ui/gl/gl_image_memory.cc

Index: ui/gl/gl_image_memory.cc
diff --git a/ui/gl/gl_image_memory.cc b/ui/gl/gl_image_memory.cc
index a29a388585fcd41406455446d0156f27deb0075d..cabc6a0972ceabbd5e91b66832903573fccef163 100644
--- a/ui/gl/gl_image_memory.cc
+++ b/ui/gl/gl_image_memory.cc
@@ -26,7 +26,7 @@ bool ValidInternalFormat(unsigned internalformat) {
     case GL_COMPRESSED_RGB_S3TC_DXT1_EXT:
     case GL_COMPRESSED_RGBA_S3TC_DXT5_EXT:
     case GL_ETC1_RGB8_OES:
-    case GL_RED:
+    case GL_R8:

[Zhenyao Mo, 2016/02/22 22:53:08]

Please also keep GL_RED

     case GL_RGB:
     case GL_RGBA:
     case GL_BGRA_EXT:
@@ -99,7 +99,9 @@ GLenum TextureFormat(BufferFormat format) {
     case BufferFormat::ETC1:
       return GL_ETC1_RGB8_OES;
     case BufferFormat::R_8:
-      return GL_RED;
+      return gfx::GLContext::GetCurrent()->GetVersionInfo()->IsES3Capable()
+                 ? GL_R8
+                 : GL_RED;
     case BufferFormat::RGBA_4444:
     case BufferFormat::RGBA_8888:
       return GL_RGBA;
@@ -125,10 +127,11 @@ GLenum DataFormat(BufferFormat format) {
       return GL_RGBA;
     case BufferFormat::BGRX_8888:
       return GL_BGRA_EXT;
+    case BufferFormat::R_8:
+      return GL_RED;

[Zhenyao Mo, 2016/02/22 22:53:08]

Why not let TextureFormat() deal with it here?

[Daniele Castagna, 2016/02/22 23:16:33]

TextureFormat returns GL_R8 for ES3.
IIUC DataFormat (that is passed to teximage2d as format) can't be R8 but should
be RED in ES3:
https://www.khronos.org/opengles/sdk/docs/man3/html/glTexImage2D.xhtml
I might be wrong and this seems pretty confusing since they allowed sized
formats in ES2 (they had to since format had to be the same as internalformat)
but it seems like in ES3 they restricted the values for format.

     case BufferFormat::RGBA_4444:
     case BufferFormat::RGBA_8888:
     case BufferFormat::BGRA_8888:
-    case BufferFormat::R_8:
     case BufferFormat::ATC:
     case BufferFormat::ATCIA:
     case BufferFormat::DXT1: