Called after a navigation has been committed and before the browser begins
loading contents in the frame. The |frame| value will never be NULL --
call the is_main() function to check if this frame is the main frame.
|transition_type| provides information about the source of the navigation
and an accurate value is only available in the browser process. Multiple
frames may be loading at the same time. Sub-frames may start or continue
loading after the main frame load has ended. This function will not be
called for same page navigations (fragments, history state, etc.) or for
navigations that fail or are canceled before commit. For notification of
overall browser load status use OnLoadingStateChange instead.
Called after a navigation has been committed and before the browser begins loading contents in the frame. The |frame| value will never be NULL -- call the is_main() function to check if this frame is the main frame. |transition_type| provides information about the source of the navigation and an accurate value is only available in the browser process. Multiple frames may be loading at the same time. Sub-frames may start or continue loading after the main frame load has ended. This function will not be called for same page navigations (fragments, history state, etc.) or for navigations that fail or are canceled before commit. For notification of overall browser load status use OnLoadingStateChange instead.