Revert "Introducing ContentGetParserOutput hook."

This change removed getHtml(), but not the call to it from fillParserOutput.
It has a few other issues that I'll flag in-line after deploying the revert.

This reverts commit fda090a7e7f85f146ec84798fda45232ab67613e

Bug: 49398
Change-Id: Idcef8d4cedc7c03f72bc1743e0f89cc5ed4ad7a7