OnContextCreated not always called when LoadUrl causes creation of new Renderer process

[cztomczak]

Noticed this issue while investigating Issue #406 ("The loss of javascript bindings when navigation to a different address occurs that forces creation of new renderer process"). Tried to do js rebindings in OnContextCreated callback.

Debug it further here:

cefpython/src/client_handler/client_handler.cpp

Line 47 in a010e68

// Frame was already destroyed while IPC messaging was

Maybe the "frameId" variable contains an invalid value. I know that sometimes frame identifiers in CEF have negative values when frame is still being initialized. Maybe a fix for that would be to pass that negative identifier as frame parameter to OnContextCreated and let user code handle the case when Frame object is not available. At least OnContextCreated would be called for such case (useful for main frame at least).