DCHECK(created_handle_) crash in scheme_handler_factory.cpp when CefSchemeHandlerFactory serves a browser-independent CefURLRequest #24

Summary

Found while adding coverage for native/url_request_client.cpp (a CefURLRequest is explicitly documented as "not associated with a browser instance"). Registering a global CefApp.registerSchemeHandlerFactory() and then using it to serve a standalone CefURLRequest (rather than a browser navigation) crashes the Debug build:

FATAL:native/jni_scoped_helpers.h:639] Check failed: created_handle_.

Root cause

native/scheme_handler_factory.cpp's SchemeHandlerFactory::Create():

ScopedJNIFrame jframe(env, frame);
jframe.SetTemporary();

calls SetTemporary() unconditionally. ScopedJNIObject's constructor only sets created_handle_ = true when its obj (here, frame) is non-null:

if (obj) {
  jhandle_ = NewJNIObject(env_, jni_class_name);
  if (jhandle_) {
    created_handle_ = true;
    ...

For a standalone CefURLRequest, CEF calls CefSchemeHandlerFactory::Create() with a null frame (there is no real CefFrame -- no browser navigation is involved), so created_handle_ stays false, and the subsequent unconditional jframe.SetTemporary() trips DCHECK(created_handle_) in SetTemporary() itself (jni_scoped_helpers.h:639).

Impact

Debug/ENABLE_COVERAGE-build only (release builds don't compile DCHECKs in, per this fork's usual pattern for this class of bug -- see #9/#20/#21). Any application combining a globally-registered CefSchemeHandlerFactory with a browser-independent CefURLRequest against a matching scheme/domain would hit this in a Debug CEF build.

Suggested fix

Guard both SetTemporary() calls in SchemeHandlerFactory::Create() on whether the corresponding ScopedJNIObject actually got a handle, e.g.:

ScopedJNIFrame jframe(env, frame);
if (frame) jframe.SetTemporary();

(and the same for jrequest, if request can plausibly be null too -- not confirmed either way this session).

Repro

CefURLRequestTest.realCompletionFiresRequestCompleteAndDownloadData() in this fork -- registers a scheme handler factory, then creates a standalone CefURLRequest against a matching URL. Currently @Disabled for the Debug/coverage build; passes cleanly in the Release build (no DCHECKs compiled in), confirmed via repeated full-suite runs.