Use DownloadItem::GetState() in chrome/

Stop using DownloadItem::Is*() functions that have an equivalent
state exposed via GetState(). Rationale is that there shouldn't be
multiple ways of getting the same state information.

To make review easier, this patch covers the remaining cases inside
chrome/. Changing content/ and DownloadItem itself to remove
the Is*() functions will come later.

TEST=browser_tests and unit_tests both with *Download*:*SavePage* filters

Review URL:

git-svn-id: svn:// 0039d316-1c4b-4281-b951-d872f2087c98
13 files changed