message: Make MetalBackend require BGRA8 swapchain
diff: @@ -70,7 +70,7 @@ namespace utils {
  nxtSwapChainError Configure(nxtTextureFormat format, nxtTextureUsageBit,
  uint32_t width, uint32_t height) {
  - if (format != NXT_TEXTURE_FORMAT_R8_G8_B8_A8_UNORM) {
  + if (format != NXT_TEXTURE_FORMAT_B8_G8_R8_A8_UNORM) {
  return "unsupported format";
  }
  ASSERT(width > 0);
  @@ -137,7 +137,7 @@ namespace utils {
  }
  nxtTextureFormat GetPreferredSwapChainTextureFormat() override {
  - return NXT_TEXTURE_FORMAT_R8_G8_B8_A8_UNORM;
  + return NXT_TEXTURE_FORMAT_B8_G8_R8_A8_UNORM;
  }
  private:
  