redo r137692 and r137791 which were speculatively reverted

redo r137692 and r137791 which were speculatively reverted
but turned out not to be causing breakage (although the former had caused some failures, the latter fixed it).

convert chromeos file manager to loadTimeData
    
    BUG=122753
TEST=manual,unit

change type of fileBrowserApi.getStrings
    
it can get things that aren't necessarily strings. It's a dictionary of all types.
    
    BUG=none
    TEST=SelectFileDialogExtensionBrowserTest.OpenSingletonTabAndCancel and others on chromiumOS dbg

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=137956

[Evan Stade, 2012-05-18 19:16:07]

TBR

[Evan Stade, 2012-05-18 19:16:07]

TBR