Check for invalid use of data frame opcodes.

Text and Binary opcodes cannot appear in the middle of a message, and
the Continuation opcode cannot appear at the start.

Fail the channel if violations of this rule are found.

BUG=343105
TEST=net_unittests, layout tests

Review URL: https://codereview.chromium.org/157033013

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@252001 0039d316-1c4b-4281-b951-d872f2087c98
Delete D-Bus clients before shutting down the system bus

Previously, D-Bus clients were deleted after the system bus was
shut down. This order was not desirable because D-Bus clients
could access the system bus in their destructors, even though the
system bus was already shut down.

BUG=344270
TEST=Chrome shuts down cleanly as before
R=hashimoto@chromium.org, stevenjb@chromium.org

Review URL: https://codereview.chromium.org/166593005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@252002 0039d316-1c4b-4281-b951-d872f2087c98
Add UseCounter labels.

BUG=34815

Review URL: https://codereview.chromium.org/166233002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@252003 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 252003
Remove --disable-drive flag and flags section in drive-internals.

This is a part of the flag clean up effort.
Since --disable-drive flag is now a user configurable (by chrome:settings)
preference, we don't need a flag.

BUG=344738
TBR=mnissler@chromium.org

Review URL: https://codereview.chromium.org/171843003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@252004 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 252004