Enable side-by-side beta and dev channels.

chrome/test/mini_installer/config/chrome_beta_not_installed.prop

Index: chrome/test/mini_installer/config/chrome_beta_not_installed.prop
diff --git a/chrome/test/mini_installer/config/chrome_beta_not_installed.prop b/chrome/test/mini_installer/config/chrome_beta_not_installed.prop
new file mode 100644
index 0000000000000000000000000000000000000000..302fe79010907f490b68b967a15c7de85c983c5d
--- /dev/null
+++ b/chrome/test/mini_installer/config/chrome_beta_not_installed.prop
@@ -0,0 +1,19 @@
+{
+  "Condition": "'$BRAND' == 'Google Chrome'",
+  "Files": {
+    "$LOCAL_APPDATA\\$CHROME_DIR_BETA\\Application": {
+      "exists": false
+    }
+  },
+  "RegistryEntries": {
+    "HKEY_CURRENT_USER\\$CHROME_UPDATE_REGISTRY_SUBKEY_BETA": {
+      "exists": "forbidden"
+    },
+    "HKEY_CURRENT_USER\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Uninstall\\$CHROME_LONG_NAME_BETA": {
+      "exists": "forbidden"
+    },
+    "HKEY_CURRENT_USER\\Software\\Classes\\$CHROME_SHORT_NAME_BETA$USER_SPECIFIC_REGISTRY_SUFFIX": {
+      "exists": "forbidden"
+    }
+  }
+}