Two fixes to touch selection:

1. When showing the context menu, pass the correct menu position to the
controller.
2. If none of the touch selection end points is in view, dont show the
selection menu.
Also, NativeTextfieldViews should not show "Select All" option in the
menu if there is nothing to select.

BUG=115237


Review URL: https://chromiumcodereview.appspot.com/12388011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@185349 0039d316-1c4b-4281-b951-d872f2087c98