Disable the AppKeepAliveService.

Keeping Chrome alive while packaged app background pages allowed apps to
keep the browser process alive with no visible windows or tray icons.
This disables that keep alive until a decision is reached on how to
handle app quits in a way that avoids this issue.

BUG=326040

Review URL: https://codereview.chromium.org/94113003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@239106 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 239106
Wait for Preference Syncing To Start Before Checking Welcome Notification Preferences

Starting up the Chrome Now Extension and Preference Syncing occur at the same
time. As a result, there is a race condition between checking the preferences
to show the welcome notification and syncing the preferences that determine
if we should show the welcome notification.

On Chrome runs with no existing profile data, when you sign in with a user
that previously saw the welcome notification, by the time Chrome Now displayed
its first card, the preferences weren't yet synced. This resulted in showing
the welcome notification.

The preference sync marks the welcome notification as shown
(kWelcomeNotificationDismissed), and the preference listener promptly hides
the welcome notification. This results in a welcome notification that is
shown and then quickly hidden away.

This change adds some waiting logic to the Welcome Notification. In short,
if the preferences are not yet syncing, wait until they are before checking
the dismissal preference.

BUG=318400

Review URL: https://codereview.chromium.org/100373003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@239107 0039d316-1c4b-4281-b951-d872f2087c98
UDPEcho* tests were deleted. Removing the entry for them.

R=jar@chromium.org
BUG=255771

Review URL: https://codereview.chromium.org/104863003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@239108 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 239108
[webcrypto] Implicitly set public keys to extractable.

There was consensus on this issue during TPAC, and this behavior will be called out in a forthcoming spec update.

See also: https://www.w3.org/Bugs/Public/show_bug.cgi?id=23695

BUG=245025

Review URL: https://codereview.chromium.org/104923004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@239109 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 239109