That was apparently not Google's intent, and the claim itself would have been ridiculous. Google realized what had occurred and claims the license was solely the “stock” option they use on other services, picked for simplicity. As a result they will be revising that section of the license for Chrome. The retroactive change has already been applied, which has caused the phrasing of the license to change. The change is significant, now much friendlier, saying that any content you own remains yours.
This will certainly put the minds of those who were upset by the license wording at ease.