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/ctocpp/browser_host_ctocpp.cc

@@ -9,7 +9,7 @@
 // implementations. See the translator.README.txt file in the tools directory
 // for more information.
 //
-// $hash=736aa196beae8c3c35ef330eb78fb0908fccf70b$
+// $hash=da0fdd0a724301aa3ca12055bce970b9d3d0f708$
 //
 
 #include "libcef_dll/ctocpp/browser_host_ctocpp.h"
@@ -1296,6 +1296,24 @@ void CefBrowserHostCToCpp::ExecuteChromeCommand(
   _struct->execute_chrome_command(_struct, command_id, disposition);
 }
 
+NO_SANITIZE("cfi-icall")
+bool CefBrowserHostCToCpp::IsRenderProcessUnresponsive() {
+  shutdown_checker::AssertNotShutdown();
+
+  cef_browser_host_t* _struct = GetStruct();
+  if (CEF_MEMBER_MISSING(_struct, is_render_process_unresponsive)) {
+    return false;
+  }
+
+  // AUTO-GENERATED CONTENT - DELETE THIS COMMENT BEFORE MODIFYING
+
+  // Execute
+  int _retval = _struct->is_render_process_unresponsive(_struct);
+
+  // Return type: bool
+  return _retval ? true : false;
+}
+
 // CONSTRUCTOR - Do not edit by hand.
 
 CefBrowserHostCToCpp::CefBrowserHostCToCpp() {}