Blamed for sparking some of the most destructive blazes in California history, Pacific Gas and Electric Co. and its parent company, PG&E Corp., reported Thursday that they will take a $2.5 billion charge to cover expected losses from October’s deadly Wine Country wildfires. And they warned investors that the financial pain may just be beginning. The damage charge, which will be recorded in the current quarter, is larger than PG&E Corp.’s 2017 profit of $1.66 billion.