[web] fix device lost handler

Author: fs-eire

cmake/external/onnxruntime_external_deps.cmake

@@ -752,6 +752,16 @@ if (onnxruntime_USE_WEBGPU)
           #
           ${Patch_EXECUTABLE} --binary --ignore-whitespace -p1 < ${PROJECT_SOURCE_DIR}/patches/dawn/safari_polyfill.patch &&
 
+          # The dawn_device_lost_keepalive.patch contains the following changes:
+          #
+          # - (private) Fix premature ABORT when device.lost fires in callUserCallback
+          #   The device.lost handler was wrapped in callUserCallback without runtimeKeepalivePush/Pop,
+          #   causing maybeExit() to trigger _exit(0) and set ABORT=true when runtimeKeepaliveCounter
+          #   was 0. This silently dropped all subsequent WebGPU callbacks (e.g. requestAdapter),
+          #   breaking session re-creation after device destruction.
+          #
+          ${Patch_EXECUTABLE} --binary --ignore-whitespace -p1 < ${PROJECT_SOURCE_DIR}/patches/dawn/dawn_device_lost_keepalive.patch &&
+
           # The dawn_dxc_output_dir.patch contains the following changes:
           #
           # - (private) Fix DXC output directory for RelWithDebInfo and MinSizeRel configs

cmake/patches/dawn/dawn_device_lost_keepalive.patch

@@ -0,0 +1,22 @@
+diff --git a/third_party/emdawnwebgpu/pkg/webgpu/src/library_webgpu.js b/third_party/emdawnwebgpu/pkg/webgpu/src/library_webgpu.js
+--- a/third_party/emdawnwebgpu/pkg/webgpu/src/library_webgpu.js
++++ b/third_party/emdawnwebgpu/pkg/webgpu/src/library_webgpu.js
+@@ -876,9 +876,11 @@
+ #if ASSERTIONS
+         assert(deviceLostFutureId);
+ #endif
+-        // Don't keepalive here, because this isn't guaranteed to ever happen.
++        // Keep the runtime alive until device.lost resolves, to prevent
++        // maybeExit() from triggering premature ABORT during callUserCallback.
++        {{{ runtimeKeepalivePush() }}}
+         WebGPU.Internals.futureInsert(deviceLostFutureId, device.lost.then((info) => {
+           // If the runtime has exited, avoid calling callUserCallback as it
+           // will print an error (e.g. if the device got freed during shutdown).
+@@ -891,6 +893,7 @@
+               {{{ gpu.passAsPointer('messagePtr') }}});
+             stackRestore(sp);
+           });
++          {{{ runtimeKeepalivePop() }}}
+         }));
+ 
+         // Set up uncaptured error handlers.