I hold an Indian passport and have a US H1B visa. I have a layover of 4 hrs in Toronto while travelling to Frankfurt. I want to know if I will require Transit visa and if so how much time it will take for processing. I tried calling the airline and the embassy but no luck yet. I am traveling on the 15th Dec 2019.
Indian citizens need a visa to enter or transit Canada, even if resident in the USA. (Permanent residents with a green card don't need a visa though.)
Looking up visa processing times for temporary resident visas (the category under which a Canadian transit visa exists in Canadian law) shows the processing time in the USA is currently 14 days.
It seems unlikely that you will be able to obtain the transit visa in time for your trip. It would be a good idea to change your flights to an itinerary which does not transit Canada.