Add CrOS's dbus-c++ to Chromium Linux. This is needed to build mtpd.

DEPS

 # When adding a new dependency, please update the top-level .gitignore file
 # to list the dependency's destination directory.
 
 vars = {
   # Use this googlecode_url variable only if there is an internal mirror for it.
   # If you do not know, use the full path while defining your new deps entry.
   "googlecode_url": "http://%s.googlecode.com/svn",
   "sourceforge_url": "http://%(repo)s.svn.sourceforge.net/svnroot/%(repo)s",
   "webkit_trunk": "http://svn.webkit.org/repository/webkit/trunk",
   "nacl_trunk": "http://src.chromium.org/native_client/trunk",
@@ skipping 507 matching lines @@
 
     "src/third_party/WebKit/Tools/gdb":
       Var("webkit_trunk") + "/Tools/gdb@" + Var("webkit_revision"),
 
     "src/third_party/gold":
       "/trunk/deps/third_party/gold@149858",
 
     "src/third_party/libmtp":
       "/trunk/deps/third_party/libmtp@160216",
 
+    # Used on Linux only. CrOS already has a copy.
+    "src/third_party/cros_dbus_cplusplus/source":
+      Var("chromiumos_git") + "/third_party/dbus-cplusplus.git" +
+      "@5e8f6d9db5c2abfb91d91f751184f25bb5cd0900",
+
     # For Linux and Chromium OS.
     "src/third_party/cros_system_api":
       Var("chromiumos_git") + "/platform/system_api.git" +
       "@572f3ee95be807777dced75795eb916ce53ac3b9",
   },
   "android": {
     "src/third_party/freetype":
       Var("chromium_git") + "/chromium/src/third_party/freetype.git" +
       "@41c2c4116acca09389cc5fe2ea393eaada546422",
 
@@ skipping 71 matching lines @@
     "pattern": ".",
     "action": ["python", "src/build/util/lastchange.py",
                "-o", "src/build/util/LASTCHANGE"],
   },
   {
     # A change to a .gyp, .gypi, or to GYP itself should run the generator.
     "pattern": ".",
     "action": ["python", "src/build/gyp_chromium"],
   },
 ]