Obama, Calderon, Harper talk trade, energy  MARK S. SMITH
Associated Press Published:   The session at the White House is
a make-good for a planned meeting last November in Hawaii on the
sidelines of the Asia-Pacific summit. Obama ended up meeting
just with Canadian Prime Minister Stephen Harper when Mexican
President Felipe Calderon's top deputy was killed in a
helicopter crash.  Sure to feature prominently in Monday's Oval
Office session: Mexico's role as a major oil exporter and the
controversial Keystone XL oil pipeline from Canada that Obama
has shelved pending further review.   The pipeline would link
Alberta's oil sands to the U.S. Gulf Coast, but
environmentalists fear both its local impact and a major uptick
in greenhouse gases blamed for global warming.  Harper has
voiced disappointment with Obama's decision. He also visited
China in February to explore alternatives. Canada has the
world's third-largest oil reserves -- more than 170 billion
barrels -- after Saudi Arabia and Venezuela, and daily prod