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It looks ECORE_WL2_EVENT_SELECTION_DATA_READY has been deprecated since a very long time ago.
Change to ECORE_WL2_EVENT_OFFER_DATA_READY for Paste operation.

+ Depending on the environment, such as whether cbhm is used or not,
the length received as an event may be string length or buffer length.
Add null validation to the event handler to ensure it works.

Currently known exception cases are resolved,
but this logic may need to be modified if another exception appears.

This reverts commit 9900645a13deda1aa7cdbe35ceab1c84d97cb60d.

Change-Id: Idf99fec07524bab8b6338b7abc7c235f3ddc6d17