Let DCHECK in non-official-release build be opt-in with dcheck_always_on=1 only

- Remove DCHECK in non-official-release build by default
- Gyp variable dcheck_always_on=1 (existing) forces to enable DCHECK
  in release build
- Remove flag --enable-dcheck

Other effects/notes:
- Now allow "buildtype=Official dcheck_always_on=1" (which will
  enable DCHECK in official build) combination.
- Gyp variable logging_like_official_build no longer has an effect
- Leave DCHECK_IS_ON() unchanged. May deal with it in a later change
  if needed.

This won't affect bots which use dcheck_always_on=1.

BUG=350462
TEST=LoggingTest.Dcheck
R=thakis@chromium.org
TBR=darin,sehr (command line changes in components/nacl and mojo)

Review URL: https://codereview.chromium.org/189603007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255987 0039d316-1c4b-4281-b951-d872f2087c98
kiosk: Fix network check skipped regression.

Fix the the regression by providing a more reasonable default value
for platform apps' default offline_enabled value: Apps default to
being offline enabled unless webview permission is requested.

BUG=349200,350129
TEST=ExtensionManifestOfflineEnabledTest.* and KioskTest.*LaunchAppNetworkDown

Review URL: https://codereview.chromium.org/181233007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255988 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 255987
SVN changes up to revision 255988