Increase shards level for browser_tests on Linux ChromiumOS Tests (dbg)(1)

testing/buildbot/chromium.chromiumos.json

 {
   "Linux ChromiumOS Builder": {
     "additional_compile_targets": [
       "All"
     ]
   },
   "Linux ChromiumOS Ozone Tests (1)": {
     "gtest_tests": [
       {
         "swarming": {
@@ skipping 896 matching lines @@
       },
       {
         "swarming": {
           "can_use_on_swarming_builders": true
         },
         "test": "base_unittests"
       },
       {
         "swarming": {
           "can_use_on_swarming_builders": true,
-          "shards": 10
+          "shards": 20
         },
         "test": "browser_tests"
       },
       {
         "swarming": {
           "can_use_on_swarming_builders": true
         },
         "test": "cacheinvalidation_unittests"
       },
       {
@@ skipping 261 matching lines @@
       },
       {
         "swarming": {
           "can_use_on_swarming_builders": true
         },
         "test": "wm_unittests"
       }
     ]
   }
 }