Add callbacks for unresponsive render process (fixes #3661)

The client can optionally wait or terminate the render process.

Expose process exit codes via OnRenderProcessTerminated and
CefGetExitCode (fixes #2126).

cefclient: Add a new https://tests/hang page for testing hang behavior.

cefclient: Move message and resource handling to a new BaseClientHandler
class to support loading of test pages in default Chrome UI windows.

libcef_dll/wrapper/libcef_dll_wrapper.cc

@@ -9,7 +9,7 @@
 // implementations. See the translator.README.txt file in the tools directory
 // for more information.
 //
-// $hash=f2b284f21cdb59e621ecddbe2f07392d24d48ddd$
+// $hash=23f943f8e59a48f29ba3095642bc05d7f987a2f2$
 //
 
 #include "include/capi/cef_app_capi.h"
@@ -106,6 +106,16 @@ CEF_GLOBAL bool CefInitialize(const CefMainArgs& args,
   return _retval ? true : false;
 }
 
+NO_SANITIZE("cfi-icall") CEF_GLOBAL int CefGetExitCode() {
+  // AUTO-GENERATED CONTENT - DELETE THIS COMMENT BEFORE MODIFYING
+
+  // Execute
+  int _retval = cef_get_exit_code();
+
+  // Return type: simple
+  return _retval;
+}
+
 NO_SANITIZE("cfi-icall") CEF_GLOBAL void CefShutdown() {
   // AUTO-GENERATED CONTENT - DELETE THIS COMMENT BEFORE MODIFYING