Check null return for CreateTextureWrapper

This seems like one of those cases where the MediaError class could
come in handy, wink wink.

Bug: 1025102
Change-Id: I4cfa4b8d1c8ae68e40369659991c511cd412d510
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1918680
Commit-Queue: Frank Liberato <liberato@chromium.org>
Reviewed-by: Frank Liberato <liberato@chromium.org>
Cr-Commit-Position: refs/heads/master@{#715747}

media/gpu/windows/d3d11_video_decoder.cc

@@ -616,6 +616,10 @@ void D3D11VideoDecoder::CreatePictureBuffers() {
   for (size_t i = 0; i < TextureSelector::BUFFER_COUNT; i++) {
     auto tex_wrapper = texture_selector_->CreateTextureWrapper(
         device_, video_device_, device_context_, in_texture, size);
+    if (!tex_wrapper) {
+      NotifyError("Unable to allocate a texture for a CopyingTexture2DWrapper");
+      return;
+    }
 
     picture_buffers_.push_back(
         new D3D11PictureBuffer(std::move(tex_wrapper), size, i));