[Perf Waterfall] Add startup.mobile to weblayer bot.

Bug: 1026327

Change-Id: Ia6a81e063cee197e3487bc408ac2456465c67751
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1948236
Commit-Queue: Caleb Rouleau <crouleau@chromium.org>
Reviewed-by: John Chen <johnchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#721286}

tools/perf/core/bot_platforms.py

@@ -193,7 +193,8 @@ _ANDROID_PIXEL2_WEBVIEW_BENCHMARK_CONFIGS = (
     _OFFICIAL_EXCEPT_DISPLAY_LOCKING_JETSTREAM2)
 _ANDROID_PIXEL2_WEBLAYER_BENCHMARK_CONFIGS = frozenset([
     _GetBenchmarkConfig('system_health.common_mobile', True),
-    _GetBenchmarkConfig('system_health.memory_mobile', True)])
+    _GetBenchmarkConfig('system_health.memory_mobile', True),
+    _GetBenchmarkConfig('startup.mobile')])
 _ANDROID_NEXUS5X_FYI_BENCHMARK_CONFIGS = frozenset([
      # Running a sample benchmark to help testing out the work on
      # trace_processor_shell: crbug.com/1028612

tools/perf/core/shard_maps/android-pixel2_weblayer-perf_map.json

 {
     "0": {
         "benchmarks": {
+            "startup.mobile": {
+                "abridged": false
+            },
             "system_health.common_mobile": {
-                "end": 18,
+                "abridged": true
+            },
+            "system_health.memory_mobile": {
+                "end": 1,
                 "abridged": true
             }
         }
     },
     "1": {
         "benchmarks": {
-            "system_health.common_mobile": {
-                "begin": 18,
+            "system_health.memory_mobile": {
+                "begin": 1,
+                "end": 12,
                 "abridged": true
             }
         }
@@ -18,7 +25,8 @@
     "2": {
         "benchmarks": {
             "system_health.memory_mobile": {
-                "end": 13,
+                "begin": 12,
+                "end": 24,
                 "abridged": true
             }
         }
@@ -26,20 +34,20 @@
     "3": {
         "benchmarks": {
             "system_health.memory_mobile": {
-                "begin": 13,
+                "begin": 24,
                 "abridged": true
             }
         }
     },
     "extra_infos": {
-        "num_stories": 56,
-        "predicted_min_shard_time": 546,
-        "predicted_min_shard_index": 2,
-        "predicted_max_shard_time": 710.0,
-        "predicted_max_shard_index": 1,
-        "shard #0": 636.0,
-        "shard #1": 710.0,
-        "shard #2": 546,
-        "shard #3": 630
+        "num_stories": 60,
+        "predicted_min_shard_time": 1374.0,
+        "predicted_min_shard_index": 3,
+        "predicted_max_shard_time": 1470.0,
+        "predicted_max_shard_index": 2,
+        "shard #0": 1400.0,
+        "shard #1": 1458.0,
+        "shard #2": 1470.0,
+        "shard #3": 1374.0
     }
 }
\ No newline at end of file