Enable localization of default downloaded filename.

Instead of localizing "download" string in net_util.cc, make a caller,
download_manger, provide a localized string.

BUG=25289
TEST=NetUtilTest.GetSuggestedFilename,DownloadManagerTest.TestDownloadFilename

Original patch by hayato@google.com at:
http://codereview.chromium.org/343014/show

Review URL: http://codereview.chromium.org/367003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@30971 0039d316-1c4b-4281-b951-d872f2087c98

• app/os_exchange_data_provider_win.cc[diff]
• chrome/app/generated_resources.grd[diff]
• chrome/browser/bookmarks/bookmark_utils.cc[diff]
• chrome/browser/cocoa/web_drag_source.mm[diff]
• chrome/browser/download/download_manager.cc[diff]
• chrome/browser/download/save_package.cc[diff]
• chrome/browser/views/tab_contents/tab_contents_view_win.cc[diff]
• net/base/net_util.cc[diff]
• net/base/net_util.h[diff]
• net/base/net_util_unittest.cc[diff]
• webkit/glue/weburlloader_impl.cc[diff]