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In the interest of phasing out the totally unnecessary
*Chrome*ExtensionFunction base classes, this establishes a
ChromeExtensionFunctionDetails object which can be created
by extension function implementations in //chrome who need
access to Chrome-specific details.

This object can be very easily composed into such function
implementations such that they can move away from using
e.g. ChromeAsyncExtensionFunction or
ChromeUIThreadExtensionFunction as a base class and instead
rely on more universal and generic ExtensionFunction and its
immediate derivatives.

A conversion of the tabs API ExecuteCodeInTabFunction is
included for demonstration purposes.

BUG=None
R=scheib@chromium.org
CC=lfg@chromium.org

Review URL: https://codereview.chromium.org/543873002

Cr-Commit-Position: refs/heads/master@{#293570}