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:
     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: