[Android] Add context manager to record logcat during step(s).

scripts/slave/recipes/chromium.expected/full_chromium_webkit_WebKit_Android__Nexus4_.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "[BUILD]/scripts/slave/bot_update.py",
       "--master",
       "chromium.webkit",
       "--builder",
       "WebKit Android (Nexus4)",
@@ skipping 424 matching lines @@
       "[\"07a00ca4\"]",
       "chromium.webkit",
       "WebKit Android (Nexus4)",
       "--blacklist-file",
       "[SLAVE_BUILD]/src/out/bad_devices.json"
     ],
     "cwd": "[SLAVE_BUILD]",
     "name": "spawn_device_monitor"
   },
   {
+    "cmd": [],
+    "cwd": "[SLAVE_BUILD]",
+    "name": "blink_heap_unittests"
+  },
+  {
+    "cmd": [
+      "[BUILD]/scripts/slave/daemonizer.py",
+      "--",
+      "[SLAVE_BUILD]/src/build/android/adb_logcat_monitor.py",
+      "[TMP_BASE]/test_logcat_tmp_1"
+    ],
+    "cwd": "[SLAVE_BUILD]",
+    "env": {
+      "PATH": "[SLAVE_BUILD]/src/third_party/android_tools/sdk/platform-tools:[SLAVE_BUILD]/src/build/android:%(PATH)s"
+    },
+    "name": "blink_heap_unittests.spawn_logcat_monitor",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
     "cmd": [
       "python",
       "-u",
       "[SLAVE_BUILD]/src/build/android/test_runner.py",
       "gtest",
       "-s",
       "blink_heap_unittests",
       "--blacklist-file",
       "[SLAVE_BUILD]/src/out/bad_devices.json",
       "--verbose",
       "--release",
       "--flakiness-dashboard-server=test-results.appspot.com",
       "--json-results-file",
       "/path/to/tmp/json"
     ],
     "cwd": "[SLAVE_BUILD]",
     "env": {
       "PATH": "[SLAVE_BUILD]/src/third_party/android_tools/sdk/platform-tools:[SLAVE_BUILD]/src/build/android:%(PATH)s"
     },
-    "name": "blink_heap_unittests"
+    "name": "blink_heap_unittests.blink_heap_unittests",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
   },
   {
     "cmd": [
+      "python",
+      "-u",
+      "[BUILD]/scripts/slave/tee.py",
+      "/path/to/tmp/logcat",
+      "--",
+      "[SLAVE_BUILD]/src/build/android/adb_logcat_printer.py",
+      "[TMP_BASE]/test_logcat_tmp_1"
+    ],
+    "cwd": "[SLAVE_BUILD]",
+    "name": "blink_heap_unittests.logcat_dump",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [],
+    "cwd": "[SLAVE_BUILD]",
+    "name": "webkit_unit_tests"
+  },
+  {
+    "cmd": [
+      "[BUILD]/scripts/slave/daemonizer.py",
+      "--",
+      "[SLAVE_BUILD]/src/build/android/adb_logcat_monitor.py",
+      "[TMP_BASE]/test_logcat_tmp_2"
+    ],
+    "cwd": "[SLAVE_BUILD]",
+    "env": {
+      "PATH": "[SLAVE_BUILD]/src/third_party/android_tools/sdk/platform-tools:[SLAVE_BUILD]/src/build/android:%(PATH)s"
+    },
+    "name": "webkit_unit_tests.spawn_logcat_monitor",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [
       "python",
       "-u",
       "[SLAVE_BUILD]/src/build/android/test_runner.py",
       "gtest",
       "-s",
       "webkit_unit_tests",
       "--blacklist-file",
       "[SLAVE_BUILD]/src/out/bad_devices.json",
       "--verbose",
       "--release",
       "--flakiness-dashboard-server=test-results.appspot.com",
       "--json-results-file",
       "/path/to/tmp/json"
     ],
     "cwd": "[SLAVE_BUILD]",
     "env": {
       "PATH": "[SLAVE_BUILD]/src/third_party/android_tools/sdk/platform-tools:[SLAVE_BUILD]/src/build/android:%(PATH)s"
     },
-    "name": "webkit_unit_tests"
+    "name": "webkit_unit_tests.webkit_unit_tests",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
   },
   {
     "cmd": [
+      "python",
+      "-u",
+      "[BUILD]/scripts/slave/tee.py",
+      "/path/to/tmp/logcat",
+      "--",
+      "[SLAVE_BUILD]/src/build/android/adb_logcat_printer.py",
+      "[TMP_BASE]/test_logcat_tmp_2"
+    ],
+    "cwd": "[SLAVE_BUILD]",
+    "name": "webkit_unit_tests.logcat_dump",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [
       "python",
       "-u",
       "[BUILD]/scripts/slave/runtest.py",
       "--target",
       "Release",
       "--test-platform",
       "android",
       "--no-xvfb",
       "--factory-properties",
       "{\"blamelist\": [\"cool_dev1337@chromium.org\", \"hax@chromium.org\"], \"buildername\": \"WebKit Android (Nexus4)\", \"buildnumber\": 571, \"gs_acl\": \"public-read\", \"mastername\": \"chromium.webkit\", \"parent_build_archive_url\": \"gs://test-domain/test-archive.zip\", \"parent_buildername\": \"Android Builder\", \"parent_got_revision\": \"1111111\", \"recipe\": \"chromium\", \"slavename\": \"TestSlavename\", \"workdir\": \"/path/to/workdir/TestSlavename\"}",
@@ skipping 125 matching lines @@
       "@@@STEP_LOG_LINE@python.inline@  os.remove(report)@@@",
       "@@@STEP_LOG_END@python.inline@@@"
     ]
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]