Add support for loading extensions (issue #1947)

- Add CefRequestContext::LoadExtension, CefExtension, CefExtensionHandler and
  related methods/interfaces.
- Add chrome://extensions-support that lists supported Chrome APIs.
- Add CefBrowserHost::SetAutoResizeEnabled and CefDisplayHandler::OnAutoResize
  to support browser resize based on preferred web contents size.
- views: Add support for custom CefMenuButton popups.
- cefclient: Run with `--load-extension=set_page_color` command-line flag for
  an extension loading example. Add `--use-views` on Windows and Linux for an
  even better example.

libcef_dll/ctocpp/display_handler_ctocpp.cc

@@ -9,7 +9,7 @@
 // implementations. See the translator.README.txt file in the tools directory
 // for more information.
 //
-// $hash=3326b8685ef95a87e31c06ed4b2b7c1072e8dda2$
+// $hash=1948d2651fc5f7fd6aab7878da869b5d231b9cde$
 //
 
 #include "libcef_dll/ctocpp/display_handler_ctocpp.h"
@@ -180,6 +180,27 @@ bool CefDisplayHandlerCToCpp::OnConsoleMessage(CefRefPtr<CefBrowser> browser,
   return _retval ? true : false;
 }
 
+bool CefDisplayHandlerCToCpp::OnAutoResize(CefRefPtr<CefBrowser> browser,
+                                           const CefSize& new_size) {
+  cef_display_handler_t* _struct = GetStruct();
+  if (CEF_MEMBER_MISSING(_struct, on_auto_resize))
+    return false;
+
+  // AUTO-GENERATED CONTENT - DELETE THIS COMMENT BEFORE MODIFYING
+
+  // Verify param: browser; type: refptr_diff
+  DCHECK(browser.get());
+  if (!browser.get())
+    return false;
+
+  // Execute
+  int _retval = _struct->on_auto_resize(
+      _struct, CefBrowserCppToC::Wrap(browser), &new_size);
+
+  // Return type: bool
+  return _retval ? true : false;
+}
+
 // CONSTRUCTOR - Do not edit by hand.
 
 CefDisplayHandlerCToCpp::CefDisplayHandlerCToCpp() {}