Add jsoncpp in DEPS and the gyp file to build jsoncpp in chromium.

third_party/jsoncpp/LICENSE

+The JsonCpp library's source code, including accompanying documentation, 
+tests and demonstration applications, are licensed under the following
+conditions...
+
+The author (Baptiste Lepilleur) explicitly disclaims copyright in all 
+jurisdictions which recognize such a disclaimer. In such jurisdictions, 
+this software is released into the Public Domain.
+
+In jurisdictions which do not recognize Public Domain property (e.g. Germany as of
+2010), this software is Copyright (c) 2007-2010 by Baptiste Lepilleur, and is
+released under the terms of the MIT License (see below).
+
+In jurisdictions which recognize Public Domain property, the user of this 
+software may choose to accept it either as 1) Public Domain, 2) under the 
+conditions of the MIT License (see below), or 3) under the terms of dual 
+Public Domain/MIT License conditions described here, as they choose.
+
+The MIT License is about as close to Public Domain as a license can get, and is
+described in clear, concise terms at:
+
+   http://en.wikipedia.org/wiki/MIT_License
+   
+The full text of the MIT License follows:
+
+========================================================================
+Copyright (c) 2007-2010 Baptiste Lepilleur
+
+Permission is hereby granted, free of charge, to any person
+obtaining a copy of this software and associated documentation
+files (the "Software"), to deal in the Software without
+restriction, including without limitation the rights to use, copy,
+modify, merge, publish, distribute, sublicense, and/or sell copies
+of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+========================================================================
+(END LICENSE TEXT)
+
+The MIT license is compatible with both the GPL and commercial
+software, affording one all of the rights of Public Domain with the
+minor nuisance of being required to keep the above copyright notice
+and license text in the source code. Note also that by accepting the
+Public Domain "license" you can re-license your copy using whatever
+license you like.