Convert ipc_mojo_unittests to run exclusively on Swarming

testing/buildbot/chromium.linux.json

Index: testing/buildbot/chromium.linux.json
diff --git a/testing/buildbot/chromium.linux.json b/testing/buildbot/chromium.linux.json
index 6cba75300d81221cd3401e94524ea4870893ee92..352fb84316421537ab4969062784d8ecb9ceaade 100644
--- a/testing/buildbot/chromium.linux.json
+++ b/testing/buildbot/chromium.linux.json
@@ -13,6 +13,9 @@
         "test": "html_viewer_unittests"
       },
       {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "ipc_mojo_unittests"
       },
       {
@@ -604,6 +607,9 @@
         "test": "gfx_unittests"
       },
       {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "gl_unittests"
       },
       {
@@ -628,6 +634,9 @@
         "test": "interactive_ui_tests"
       },
       {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "ipc_mojo_unittests"
       },
       {
@@ -917,6 +926,9 @@
         "test": "gfx_unittests"
       },
       {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "gl_unittests"
       },
       {
@@ -942,6 +954,9 @@
         "test": "interactive_ui_tests"
       },
       {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "ipc_mojo_unittests"
       },
       {
@@ -1222,6 +1237,9 @@
         "test": "gfx_unittests"
       },
       {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "gl_unittests"
       },
       {
@@ -1246,6 +1264,9 @@
         "test": "interactive_ui_tests"
       },
       {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "ipc_mojo_unittests"
       },
       {