Add EXT_color_buffer_half_float extension support in GPU commandbuffer service.

gpu/command_buffer/common/gles2_cmd_utils.cc

Index: gpu/command_buffer/common/gles2_cmd_utils.cc
diff --git a/gpu/command_buffer/common/gles2_cmd_utils.cc b/gpu/command_buffer/common/gles2_cmd_utils.cc
index ef0f3ead7f6fb6ced61759439a2595b11b6dea6d..0966d1dcb9a2914c4839f534f9dae39b854c2289 100644
--- a/gpu/command_buffer/common/gles2_cmd_utils.cc
+++ b/gpu/command_buffer/common/gles2_cmd_utils.cc
@@ -228,6 +228,8 @@ int GLES2Util::GLGetNumValuesReturned(int id) const {
       return 1;
     case GL_FRAMEBUFFER_ATTACHMENT_TEXTURE_CUBE_MAP_FACE:
       return 1;
+    case GL_FRAMEBUFFER_ATTACHMENT_COMPONENT_TYPE_EXT:
+      return 1;
 
     // -- glGetFramebufferAttachmentParameteriv
     case GL_DELETE_STATUS:
@@ -461,6 +463,10 @@ size_t GLES2Util::RenderbufferBytesPerPixel(int format) {
     case GL_RGBA8_OES:
     case GL_DEPTH_COMPONENT24_OES:
       return 4;
+    case GL_RGB16F_EXT:
+      return 6;
+    case GL_RGBA16F_EXT:
+      return 8;
     default:
       return 0;
   }