chrome: Add ability to handle chrome menu/keyboard commands (fixes issue #3280)

This change adds a CefCommandHandler::OnChromeCommand callback for optionally
handling Chrome commands triggered via menus or keyboard shortcuts. Supported
command IDs are listed in a new cef_command_ids.h header file.

To test: Run `cefclient --enable-chrome-runtime --hide-controls`. Most commands
will blocked and removed from context menus.

tests/cefclient/browser/browser_window_osr_gtk.h

@@ -25,6 +25,7 @@ class BrowserWindowOsrGtk : public BrowserWindow,
   // Constructor may be called on any thread.
   // |delegate| must outlive this object.
   BrowserWindowOsrGtk(BrowserWindow::Delegate* delegate,
+                      bool with_controls,
                       const std::string& startup_url,
                       const OsrRendererSettings& settings);