Linux: Adds ACKs to ProcessSingletonLinux.

chrome/chrome.gyp

Index: chrome/chrome.gyp
diff --git a/chrome/chrome.gyp b/chrome/chrome.gyp
index 2ffa56098230b79c22a951936551802c4c202570..2dea093d4bdb11d40d9b940b584c362db104141d 100644
--- a/chrome/chrome.gyp
+++ b/chrome/chrome.gyp
@@ -3535,6 +3535,7 @@
         'browser/media_uitest.cc',
         'browser/metrics/metrics_service_uitest.cc',
         'browser/printing/printing_layout_uitest.cc',
+        'browser/process_singleton_linux_uitest.cc',
         'browser/renderer_host/resource_dispatcher_host_uitest.cc',
         'browser/sanity_uitest.cc',
         'browser/session_history_uitest.cc',
@@ -3574,6 +3575,10 @@
             'test/reliability/page_load_test.cc',
             'test/ui/layout_plugin_uitest.cc',
           ],
+        }, { # else: OS != "linux"
+          'sources!': [
+            'browser/process_singleton_linux_uitest.cc',
+          ],
         }],
         ['OS=="linux" and toolkit_views==1', {
           'dependencies': [