Enabling DetectingHeavyPages (Capping Heavy Pages) for android bots

This CL enables DetectingHeavyPages for android in
fiedtrial_testing_config.json.

Bug: 709493
Change-Id: I8896644a3838355b14b7fafb98815ddf968ae053
Reviewed-on: https://chromium-review.googlesource.com/1131687Reviewed-by: Tarun Bansal <tbansal@chromium.org>
Reviewed-by: Steven Holte <holte@chromium.org>
Commit-Queue: Ryan Sturm <ryansturm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#575490}

testing/variations/fieldtrial_testing_config.json

@@ -1326,6 +1326,21 @@
             ]
         }
     ],
+    "DetectingHeavyPages": [
+        {
+            "platforms": [
+                "android"
+            ],
+            "experiments": [
+                {
+                    "name": "Enabled",
+                    "enable_features": [
+                        "DetectingHeavyPages"
+                    ]
+                }
+            ]
+        }
+    ],
     "DownloadHomeMoreButton": [
         {
             "platforms": [