Change browser type to android-chromium

TBR=eyaich@chromium.org
NOTRY=true

Bug: 786010
Change-Id: I9d9d9d38c99537f17833fe8de0e50f95e50a8279
Reviewed-on: https://chromium-review.googlesource.com/823230Reviewed-by: Ned Nguyen <nednguyen@google.com>
Commit-Queue: Ned Nguyen <nednguyen@google.com>
Cr-Commit-Position: refs/heads/master@{#523571}

testing/buildbot/chromium.perf.fyi.json

@@ -9,7 +9,7 @@
           "-v",
           "--upload-results",
           "--output-format=chartjson",
-          "--browser=release"
+          "--browser=android-chromium"
         ],
         "isolate_name": "telemetry_perf_tests",
         "name": "experimental.startup.android.coldish",

tools/perf/chromium.perf.fyi.extras.json

@@ -351,7 +351,7 @@
           "-v",
           "--upload-results",
           "--output-format=chartjson",
-          "--browser=release"
+          "--browser=android-chromium"
         ],
         "isolate_name": "telemetry_perf_tests",
         "name": "experimental.startup.android.coldish",