Convert app_shell_unittests to run on Swarming

testing/buildbot/chromium.win.json

Index: testing/buildbot/chromium.win.json
diff --git a/testing/buildbot/chromium.win.json b/testing/buildbot/chromium.win.json
index 2729962b3ce9b707b4fe1cfa71f3276f49c1d9d3..39088f2c27b6c451eb9aa5716d046b4fae1b35ff 100644
--- a/testing/buildbot/chromium.win.json
+++ b/testing/buildbot/chromium.win.json
@@ -8,6 +8,9 @@
         "test": "accessibility_unittests"
       },
       {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "app_shell_unittests"
       },
       {
@@ -270,6 +273,9 @@
         "test": "app_list_unittests"
       },
       {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "app_shell_unittests"
       },
       {
@@ -675,6 +681,9 @@
         "test": "app_list_unittests"
       },
       {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "app_shell_unittests"
       },
       {
@@ -969,6 +978,9 @@
         "test": "accessibility_unittests"
       },
       {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "app_shell_unittests"
       },
       {
@@ -1397,6 +1409,9 @@
         "test": "accessibility_unittests"
       },
       {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "app_shell_unittests"
       },
       {