gpu: support R16 GPUMemoryBuffer

ui/gl/gl_image_io_surface.mm

Index: ui/gl/gl_image_io_surface.mm
diff --git a/ui/gl/gl_image_io_surface.mm b/ui/gl/gl_image_io_surface.mm
index fc4df49f478ff007cbbfd681ce8c63cd8493582d..c9fabee5a262ca1981680274e241c27770d08fbe 100644
--- a/ui/gl/gl_image_io_surface.mm
+++ b/ui/gl/gl_image_io_surface.mm
@@ -32,6 +32,7 @@ namespace {
 bool ValidInternalFormat(unsigned internalformat) {
   switch (internalformat) {
     case GL_RED:
+    case GL_R16_EXT:

[Ken Russell (switch to Gerrit), 2017/06/09 22:37:39]

Note: I checked CGLIOSurface.h and confirmed that the format/type/internal
format tuple (GL_UNSIGNED_SHORT, GL_RED, GL_R16) is supported. However, it was
only subsumed into the Core Profile in OpenGL 3.0. If Chrome happens to fall
back to the OpenGL compatibility profile (which is feature level 2.1 on macOS),
do we need to feature detect its availability (via GL_ARB_texture_rg)?

[riju_, 2017/06/13 15:34:14]

Thanks, I am doing the check here->
https://codereview.chromium.org/2933313003

[Ken Russell (switch to Gerrit), 2017/06/13 23:52:36]

Thanks. Reviewed that other change; it isn't necessary, since the other code
path checks for is_desktop_core_profile, which implies a minimum version of
OpenGL 3.2.

[riju_, 2017/06/14 07:14:46]

Acknowledged.

     case GL_RG:
     case GL_BGRA_EXT:
     case GL_RGB:
@@ -54,6 +55,7 @@ bool ValidFormat(gfx::BufferFormat format) {
     case gfx::BufferFormat::UYVY_422:
     case gfx::BufferFormat::YUV_420_BIPLANAR:
       return true;
+    case gfx::BufferFormat::R_16:
     case gfx::BufferFormat::RG_88:
     case gfx::BufferFormat::ATC:
     case gfx::BufferFormat::ATCIA:
@@ -75,6 +77,8 @@ GLenum TextureFormat(gfx::BufferFormat format) {
   switch (format) {
     case gfx::BufferFormat::R_8:
       return GL_RED;
+    case gfx::BufferFormat::R_16:
+      return GL_R16_EXT;
     case gfx::BufferFormat::RG_88:
       return GL_RG;
     case gfx::BufferFormat::BGRA_8888:
@@ -107,6 +111,8 @@ GLenum DataFormat(gfx::BufferFormat format) {
   switch (format) {
     case gfx::BufferFormat::R_8:
       return GL_RED;
+    case gfx::BufferFormat::R_16:
+      return GL_R16_EXT;
     case gfx::BufferFormat::RG_88:
       return GL_RG;
     case gfx::BufferFormat::BGRA_8888:
@@ -140,6 +146,8 @@ GLenum DataType(gfx::BufferFormat format) {
     case gfx::BufferFormat::R_8:
     case gfx::BufferFormat::RG_88:
       return GL_UNSIGNED_BYTE;
+    case gfx::BufferFormat::R_16:
+      return GL_UNSIGNED_SHORT;
     case gfx::BufferFormat::BGRA_8888:
     case gfx::BufferFormat::BGRX_8888:
     case gfx::BufferFormat::RGBA_8888: