General Motors Co (GM.N) Chief Executive Officer Mary Barra’s deal on Monday to return up to $10 billion to investors is a career-defining bet that she can reverse the automaker’s history of doubling down on money-losing products and failed expansion strategies. The linchpin of the strategy GM outlined to buy back $5 billion worth of shares and distribute another $5 billion in dividends to shareholders by the end of 2016 is a vow that the company will generate 20 percent or better returns on cash invested in new vehicles, advanced technology and other capital projects.