When a remote process has focus and it loses focus,
IMEStateManager::OnChangeFocusInternal() sends NOTIFY_IME_OF_BLUR via
IMEStateManager::NotifyIMEOfBlurForChildProcess(). Therefore,
sFocusedIMETabParent and sFocusedIMEWidget are set to nullptr here. So, if a
window becomes active, REQUEST_IME_TO_COMMIT_COMPOSITION in
IMEStateManager::OnChangeFocusInternal() won't work because
IMEStateManager::NotifyIME() ignores the request because of coming from wrong
process.
Therefore, IMEStateManager::OnChangeFocusInternal() needs to send
REQUEST_TO_COMMIT_COMPOSITION with proper process information which is only
stored by TextComposition instance.
MozReview-Commit-ID: KNEvOoQtK1E
--HG--
extra : rebase_source : 2d0c9297a6ffd3e7883130c80deec0479212148e
