Add support for mapping node tree on the client.

mojo/mojo_services.gypi

 {
   'targets': [
     {
       'target_name': 'mojo_echo_bindings',
       'type': 'static_library',
       'sources': [
         'services/dbus_echo/echo.mojom',
       ],
       'variables': {
         'mojom_base_output_dir': 'mojo',
@@ skipping 136 matching lines @@
       'type': 'static_library',
       'dependencies': [
         '../base/base.gyp:base',
         'mojo_shell_bindings',
         'mojo_view_manager_bindings',
         'mojo_view_manager_common',
       ],
       'sources': [
         'services/public/cpp/view_manager/lib/view.cc',
         'services/public/cpp/view_manager/lib/view_manager.cc',
+        'services/public/cpp/view_manager/lib/view_manager_observer.h',
         'services/public/cpp/view_manager/lib/view_manager_private.cc',
         'services/public/cpp/view_manager/lib/view_manager_private.h',
         'services/public/cpp/view_manager/lib/view_manager_synchronizer.cc',
         'services/public/cpp/view_manager/lib/view_manager_synchronizer.h',
         'services/public/cpp/view_manager/lib/view_tree_host.cc',
         'services/public/cpp/view_manager/lib/view_tree_node.cc',
         'services/public/cpp/view_manager/lib/view_tree_node_observer.cc',
         'services/public/cpp/view_manager/lib/view_tree_node_private.cc',
         'services/public/cpp/view_manager/lib/view_tree_node_private.h',
         'services/public/cpp/view_manager/view.h',
         'services/public/cpp/view_manager/view_manager.h',
         'services/public/cpp/view_manager/view_manager_types.h',
         'services/public/cpp/view_manager/view_tree_host.h',
         'services/public/cpp/view_manager/view_tree_node.h',
         'services/public/cpp/view_manager/view_tree_node_observer.h',
       ],
     },
     {
       'target_name': 'mojo_view_manager_lib_unittests',
       'type': 'executable',
       'dependencies': [
         '../base/base.gyp:base',
         '../base/base.gyp:test_support_base',
         '../testing/gtest.gyp:gtest',
         'mojo_environment_chromium',
         'mojo_run_all_unittests',
+        'mojo_shell_test_support',
+        'mojo_view_manager_bindings',
         'mojo_view_manager_lib',
       ],
       'sources': [
         'services/public/cpp/view_manager/tests/view_unittest.cc',
         'services/public/cpp/view_manager/tests/view_manager_unittest.cc',
         'services/public/cpp/view_manager/tests/view_tree_host_unittest.cc',
         'services/public/cpp/view_manager/tests/view_tree_node_unittest.cc',
       ],
     },
   ],
@@ skipping 81 matching lines @@
             'mojo_system_impl',
           ],
           'sources': [
             'services/dbus_echo/dbus_echo_service.cc',
           ],
         },
       ],
     }],
   ],
 }