Make WebGPU EP compatible with EP API

[fs-eire]

Description

This PR makes it possible to build WebGPU EP as an EP API based plugin EP.

Requirements

The goal of this PR is to support both building WebGPU EP as a bundled EP and an EP API based plugin EP. This approach allows:

• enabling WebGPU EP as a standalone plugin EP package for WCR usage
• graceful transition for WebGPU EP as an native EP for language binding, from the bundled EP to an EP API based plugin EP
• keep the existing usage (static library) working (majorly for web)

Design & Implementation

Instead of changing WebGPU EP from a bundled EP to an EP API based plugin EP in one shot, this PR extend WebGPU EP to support building as plugin EP.

• add a new folder include/onnxruntime/ep with a bunches of header files. Those files are not WebGPU specific. They are used for:

  • include common defines/functions/macros for plugin EP to use
  • include a few "adapter" classes that takes C-API objects to simulate ORT internal classes behaviors
  • include a few "override" classes that simulate ORT internal classes, but using implementations that only depend on C-API
  • include a special base class onnxruntime::ep::Ep to inherit from

  These header files allow a compile time "switch" to the different set of types to minimize changes to existing code. Specifically, pch.h is required to be included as PCH to make sure the "override" to take place correctly.

• add a new folder onnxruntime/core/providers/webgpu/ep for EP API implementation, specifically:

  • api.cc: implements CreateEpFactories and ReleaseEpFactory
  • ep.cc ep.h: implement class onnxruntime::webgpu::ep::Ep
  • factory.cc factory.h: implement class onnxruntime::webgpu::ep::Factory

Dependencies and Prerequisites

(unmerged changes are included as a part of current PR)

• [webgpu] refactor initialization of WebGPU Context params #26855
• [EP ABI] Add OrtKernelInfo APIs for kernel-based plugin EPs #26803
• Plugin EP API - Add OrtEp::IsConcurrentRunSupported #26859
• [EP API] extract common code for EP API adapter #26879
• [EP API] header-only adapter for EP API #26919
• Fix WebGPU EP crash on exit #27569
• [EP Plugin Adapter] support LoggingManager::HasDefaultLogger() #27587

Missing Parts

• Allow setting Global/Default EP options

[Copilot]

Pull request overview

This PR extends WebGPU EP to support building as both a bundled EP (static library) and an EP API-based plugin EP (shared library). The changes introduce a new adapter infrastructure in include/onnxruntime/ep/ that bridges C-API objects to simulate ORT internal class behaviors, enabling compile-time switching between build modes with minimal code changes.

Key changes:

• New EP adapter infrastructure with header-only wrapper classes for kernel info, context, registry, and EP interface
• WebGPU EP API implementation (api.cc, factory.cc/h, ep.cc/h) in onnxruntime/core/providers/webgpu/ep/
• Templated CPU tensor operator base classes to work with both native and adapter OpKernelInfo types
• Enhanced C API with KernelInfo_GetOperatorType, KernelInfo_GetSinceVersion, and KernelInfo_GetEp
• Test infrastructure updates including example kernel registry changes (Mul kernel renamed to BinaryOp supporting both Add and Mul)

Reviewed changes

Copilot reviewed 75 out of 75 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
include/onnxruntime/ep/*.h	New EP adapter infrastructure headers providing C-API wrappers for kernel registration and execution
onnxruntime/core/providers/webgpu/ep/*	WebGPU EP API implementation for factory, EP instance, and plugin entry points
onnxruntime/core/providers/cpu/tensor/*.h	Templated base classes for tensor ops to support both native and adapter kernel info types
onnxruntime/test/autoep/*	Test updates including BinaryOp generalization and additional test coverage
onnxruntime/core/session/*.cc	Core API additions for kernel info operator type, version, and EP retrieval

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