Style fix for history backend.

Leftover comment from https://codereview.chromium.org/108513009/.

TBR=sky@chromium.org
BUG=

Review URL: https://codereview.chromium.org/93703006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@241340 0039d316-1c4b-4281-b951-d872f2087c98
[sql] Diagnostic to track recovery crash.

There are some crashes happening in leafCursorCellDecode() which imply
that the leaf cursor is NULL.  AFAICT, this case is not possible.  Add
some code to verify whether the leaf cursor was NULL at the point it was
added to the virtual-table cursor.  If the crash moves, then there's
something wrong with leafCursorCreate(), if the crash stays in place,
there's something happening in the SQLite virtual table infrastructure.

BUG=326646

Review URL: https://codereview.chromium.org/109123002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@241341 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 241341
Pull GN binary @ 214318.

The Linux build is generated using the official build sysroot from
https://codereview.chromium.org/116803003/ which isn't checked in yet (that
change requires this new binary).

R=scottmg@chromium.org
TBR=scottmg

Review URL: https://codereview.chromium.org/117043005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@241342 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 241342