Add EXT_color_buffer_half_float extension support in GPU commandbuffer service.

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 f1f024c0dbb92e5a46664464a71959614eb05235..74f016b28b120658d17685c05cbbc7d0dff8896c 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -6923,12 +6923,7 @@ error::Error GLES2DecoderImpl::HandleReadPixels(
             GL_INVALID_VALUE, "glReadPixels", "dimensions out of range");
         return error::kNoError;
       }
-      // NOTE: Assumes the type is GL_UNSIGNED_BYTE which was true at the time
-      // of this implementation.
       if (type != GL_UNSIGNED_BYTE) {
-        LOCAL_SET_GL_ERROR(
-            GL_INVALID_OPERATION, "glReadPixels",
-            "unsupported readPixel format");
         return error::kNoError;
       }
       switch (format) {