Makes sure chrome_run target is always present

Needed so that try bots can always depend upon a chrome_run target
existing. Without this it makes detection of whether chrome is going
to be built tricky (some times it'll be chrome, othertimes
chrome_run).

BUG=407419
TEST=none
R=jam@chromium.org

Review URL: https://codereview.chromium.org/507503003

Cr-Commit-Position: refs/heads/master@{#291818}

chrome/chrome_exe.gypi

@@ -697,6 +697,16 @@
             }],
           ],
         },
+    ]}, {
+      # Used by bots so they can always depend on chrome_run target.
+      'targets': [
+        {
+          'target_name': 'chrome_run',
+          'type': 'none',
+          'dependencies': [
+            'chrome',
+          ],
+        },
       ],
     }],
   ],