[extensions] Position browser action popup correctly for RTL languages.
[extensions] Position browser action popup correctly for RTL languages.

ExtensionPopup::Show was hard coded to use BubbleBorder::TOP_RIGHT, by changing it to be dynamic that depends on UI Layout fixes this issue.

BUG=29807
TEST=Change chrome language to Arabic, install Sidewiki, the popup will position itself correctly.

Review URL: http://codereview.chromium.org/494008

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@34491 0039d316-1c4b-4281-b951-d872f2087c98

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