Experimental viewport meta tag support for desktop

Added flag to allow desktop builds to experimentally turn
on support for the viewport meta tag. The --enable-viewport
flag now turns on only support for @viewport.
--enable-viewport-meta turns on viewport meta and @viewport
support.

On Android, the viewport gets rescaled when the view is
resized, i.e. phone is rotated between landscape and
portrait. On desktop, enabling the viewport causes the page
to zoom out when the window is shrunk, rather than adding
scrollbars. To support viewport on both devices, I've added
a --main-frame-resizes-are-orientation-changes flag that should be set on
Android and not desktop. This prevents the viewport scaling
code in WebViewImpl::resize().

Enabling viewport on desktop means the page scale can
change. This causes a known issue with scrollbars where
mouse events are scaled with the page, making mouse
interaction with scrollbars broken.

This is the Chromium side of a 2-side patch
(Blink-side at https://codereview.chromium.org/40423003/)

BUG=232102

Review URL: https://codereview.chromium.org/38793007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@234617 0039d316-1c4b-4281-b951-d872f2087c98
Implement ScopedChildProcessReference class

An innocent attempt.

BUG=none

Review URL: https://codereview.chromium.org/66443002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@234618 0039d316-1c4b-4281-b951-d872f2087c98
net: don't add padding extension for SSLv3.

This is a no-op change because our SSLv3 handshakes aren't long enough to
trigger the padding extension. But, if they were, the padding extension would
break them.

BUG=315828

Review URL: https://codereview.chromium.org/66553007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@234619 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 234618
SVN changes up to revision 234619
linux_aura: Reduce static initializers.

BUG=317171
R=thakis@chromium.org

Review URL: https://codereview.chromium.org/61793011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@234622 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 234622