Change 0 to False in several grit if-expressions.

Grit r150 (https://codereview.chromium.org/156443002) starts enforcing
that if-expressions must evaluate to a boolean value. To comply, we need
to make this change in a few places:

Before: <if expr="0">
After:  <if expr="False">

Review URL: https://codereview.chromium.org/133813009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249970 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 249970
External component extensions should not have a context menu.

Like for normal component extensions, the context menu items make
little sense for an invisible extension the user has no control
over.

BUG=

Review URL: https://codereview.chromium.org/137823015

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249971 0039d316-1c4b-4281-b951-d872f2087c98
NaCl docs: fix a few more issues with the ARM sandbox documentation.

Fix some comments I had missed in:
  https://codereview.chromium.org/147803003/

R= binji@chromium.org, sbc@chromium.org, awatson@chromium.org, mackinlay@chromium.org
BUG= none
TEST= none
NOTRY=true
(documentation only change)

Review URL: https://codereview.chromium.org/144253005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249972 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 249972