[tracing] Rename WebMemoryDumpLevelOfDetail enums to match chromium Non-functional refactor to match names in the chromium repo as per crrev.com/1337943003 Just changes the names of WebMemoryDumpLevelOfDetail constants. BUG= Review URL: https://codereview.chromium.org/1349183002 git-svn-id: svn://svn.chromium.org/blink/trunk/public@202515 bbb929c8-8fbe-4397-9dbb-9b2b20218538