Fix Linux CefMainArgs empty command line; log subprocess type

cefpython.pyx: Linux was using the default CefMainArgs() constructor
(argc=0, argv=nullptr), leaving Chromium's base::CommandLine with no
program name. CEF 146 relies on a valid CommandLine::GetProgram() when
bootstrapping IPC shared-memory channels for subprocesses (global
descriptor 7). Pass argc=1, argv[0]=sys.executable so Chromium has a
proper program name to work from.

cefpython_app.cpp: change OnBeforeChildProcessLaunch log from INFO to
ERROR so the subprocess command line (including --type=) is visible in
CI output regardless of log_severity setting, aiding diagnosis.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: linesight

src/cefpython.pyx

@@ -577,8 +577,13 @@ def Initialize(applicationSettings=None, commandLineSwitches=None, **kwargs):
         cdef HINSTANCE hInstance = GetModuleHandle(NULL)
         cdef CefMainArgs cefMainArgs = CefMainArgs(hInstance)
     ELIF UNAME_SYSNAME == "Linux":
-        # TODO: use the CefMainArgs(int argc, char** argv) constructor.
-        cdef CefMainArgs cefMainArgs
+        # Pass argv[0] = Python executable so Chromium's CommandLine is
+        # initialized with a valid program name. CEF 146 relies on this for
+        # correct IPC channel bootstrap in subprocesses (global descriptor 7).
+        cdef bytes _cefMainArgv0 = sys.executable.encode('utf-8')
+        cdef char* _cefMainArgv0Ptr = _cefMainArgv0
+        cdef char** _cefMainArgv = &_cefMainArgv0Ptr
+        cdef CefMainArgs cefMainArgs = CefMainArgs(1, _cefMainArgv)
     ELIF UNAME_SYSNAME == "Darwin":
         # TODO: use the CefMainArgs(int argc, char** argv) constructor.
         cdef CefMainArgs cefMainArgs

src/subprocess/cefpython_app.cpp

@@ -204,7 +204,7 @@ void CefPythonApp::OnBeforeChildProcessLaunch(
     logMessage.append("OnBeforeChildProcessLaunch() command line: ");
     std::string clString = command_line->GetCommandLineString().ToString();
     logMessage.append(clString.c_str());
-    LOG(INFO) << logMessage.c_str();
+    LOG(ERROR) << logMessage.c_str();
 }
 
 CefRefPtr<CefPrintHandler> CefPythonApp::GetPrintHandler() {