Switch extension update manifest parse errors to LOG(WARN).
Switch extension update manifest parse errors to LOG(WARN).

Before this patch they are using ExtensionErrorReporter, but I
don't think it's actually useful for users to see them on the
chrome://extensions page. 

BUG=http://crbug.com/18565
TEST=You should no longer see messages like "Extension update
manifest parse error: Invalid codebase url"on the
chrome://extensions page.


Review URL: http://codereview.chromium.org/164008

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@22662 0039d316-1c4b-4281-b951-d872f2087c98

adobe/chromium,yitian134/chromium,ropik/chromium,ropik/chromium,gavinp/chromium,adobe/chromium,gavinp/chromium,gavinp/chromium,ropik/chromium,Crystalnix/house-of-life-chromium,gavinp/chromium,ropik/chromium,Crystalnix/house-of-life-chromium,gavinp/chromium,Crystalnix/house-of-life-chromium,yitian134/chromium,gavinp/chromium,yitian134/chromium,yitian134/chromium,ropik/chromium,adobe/chromium,adobe/chromium,adobe/chromium,adobe/chromium,adobe/chromium,yitian134/chromium,adobe/chromium,yitian134/chromium,ropik/chromium,Crystalnix/house-of-life-chromium,ropik/chromium,Crystalnix/house-of-life-chromium,yitian134/chromium,Crystalnix/house-of-life-chromium,Crystalnix/house-of-life-chromium,gavinp/chromium,yitian134/chromium,adobe/chromium,ropik/chromium,ropik/chromium,gavinp/chromium,gavinp/chromium,Crystalnix/house-of-life-chromium,yitian134/chromium,Crystalnix/house-of-life-chromium,adobe/chromium,yitian134/chromium,adobe/chromium,gavinp/chromium,Crystalnix/house-of-life-chromium,Crystalnix/house-of-life-chromium