Add ui_unittests to GN build.

ui/ui_unittests.gyp

Index: ui/ui_unittests.gyp
diff --git a/ui/ui_unittests.gyp b/ui/ui_unittests.gyp
index b186cd143c75aad490590a15979a5394595a1968..0346f5157a001ff13360c1fbc2f68d9fddc82f9f 100644
--- a/ui/ui_unittests.gyp
+++ b/ui/ui_unittests.gyp
@@ -31,6 +31,7 @@
       # iOS uses a small subset of ui. common_sources are the only files that
       # are built on iOS.
       'common_sources' : [
+        # Note: file list duplicated in GN build.
         'base/layout_unittest.cc',
         'base/l10n/l10n_util_mac_unittest.mm',
         'base/l10n/l10n_util_unittest.cc',
@@ -43,6 +44,7 @@
         'base/test/run_all_unittests.cc',
       ],
       'all_sources': [
+        # Note: file list duplicated in GN build.
         '<@(_common_sources)',
         'base/accelerators/accelerator_manager_unittest.cc',
         'base/accelerators/menu_label_accelerator_util_linux_unittest.cc',
@@ -191,11 +193,6 @@
             'events/platform/events_platform.gyp:events_platform',
           ],
         }],
-        ['use_aura==1', {
-          'sources!': [
-            'base/dragdrop/os_exchange_data_win_unittest.cc',
-          ],
-        }],
         ['chromeos==1', {
           'dependencies': [
             '../chromeos/chromeos.gyp:chromeos',
@@ -211,12 +208,6 @@
             'base/x/selection_requestor_unittest.cc',
           ],
         }],
-        ['chromeos==0 or use_x11==0', {
-          'sources!': [
-            'base/ime/chromeos/character_composer_unittest.cc',
-            'base/ime/input_method_chromeos_unittest.cc',
-          ],
-        }],
         ['use_x11==0', {
           'sources!': [
             'base/ime/composition_text_util_pango_unittest.cc',