Add webapk_client_junit_tests to bots.

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 1d92a8810527f55d152bf56adc14795e04a2cb40..33f4d85e1a874d9582a157eb56a7dc483c878201 100644
--- a/testing/buildbot/chromium.linux.json
+++ b/testing/buildbot/chromium.linux.json
@@ -193,6 +193,9 @@
       },
       {
         "test": "ui_junit_tests"
+      },
+      {
+        "test": "webapk_client_junit_tests"
       }
     ]
   },
@@ -354,6 +357,9 @@
       },
       {
         "test": "ui_junit_tests"
+      },
+      {
+        "test": "webapk_client_junit_tests"
       }
     ],
     "scripts": [
@@ -492,6 +498,9 @@
       },
       {
         "test": "ui_junit_tests"
+      },
+      {
+        "test": "webapk_client_junit_tests"
       }
     ],
     "scripts": [