[DevTools] Add canProfilePower command and plumb power handlers to RenderViewDevToolsAgentHost

BUG=337138

Review URL: https://codereview.chromium.org/190443002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255845 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 255845