Run a few more tests where it's not clear why they don't run.

- Run components_browsertests on 32-bit linux dbg main waterfall bot,
  and on the win7 and win10 dbg main waterfall bots. If the tests
  end up failing there, we can re-disable them with a link to a bug
  explaining what exactly fails.

- Run mash_unittests on the fyi Mojo ChromiumOS bot
  (suite takes seconds to run).

Bug: 843511
Change-Id: I6b529723300ade97712e5e360dfddff8d8d64c40
Reviewed-on: https://chromium-review.googlesource.com/1136464Reviewed-by: Kenneth Russell <kbr@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#575091}

testing/buildbot/chromium.fyi.json

@@ -1479,6 +1479,12 @@
         },
         "test": "interactive_ui_tests"
       },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "mash_unittests"
+      },
       {
         "swarming": {
           "can_use_on_swarming_builders": true

testing/buildbot/chromium.linux.json

@@ -2602,6 +2602,12 @@
         },
         "test": "chromedriver_unittests"
       },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "components_browsertests"
+      },
       {
         "args": [
           "--enable-features=NetworkService"

testing/buildbot/chromium.win.json

@@ -1506,6 +1506,12 @@
         },
         "test": "chromedriver_unittests"
       },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "components_browsertests"
+      },
       {
         "swarming": {
           "can_use_on_swarming_builders": true
@@ -2913,6 +2919,12 @@
         },
         "test": "chromedriver_unittests"
       },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "components_browsertests"
+      },
       {
         "args": [
           "--enable-features=NetworkService"

testing/buildbot/test_suite_exceptions.pyl

@@ -337,15 +337,6 @@
       },
     },
   },
-  'components_browsertests': {
-    'remove_from': [
-      # chromium.linux
-      'Linux Tests (dbg)(1)(32)',
-      # chromium.win
-      'Win7 Tests (dbg)(1)',
-      'Win10 Tests x64 (dbg)',
-    ],
-  },
   'components_unittests': {
     'modifications': {
       # chromium.memory
@@ -729,12 +720,6 @@
       },
     },
   },
-  'mash_unittests': {
-    'remove_from': [
-      # chromium.fyi
-      'Mojo ChromiumOS',
-    ],
-  },
   'nacl_helper_nonsfi_unittests': {
     'remove_from': [
       # chromium.memory