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

scripts/slave/recipe_modules/chromium_android/example.expected/perf_runner_basic.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "\nimport os, sys\n\nbuild_path = sys.argv[1]\nif os.path.exists(build_path):\n  for (path, dir, files) in os.walk(build_path):\n    for cur_file in files:\n      if cur_file.endswith('index.lock'):\n        path_to_file = os.path.join(path, cur_file)\n        print 'deleting %s' % path_to_file\n        os.remove(path_to_file)\n",
       "[SLAVE_BUILD]"
     ],
     "cwd": "[SLAVE_BUILD]",
     "name": "cleanup index.lock",
@@ skipping 260 matching lines @@
       "@@@STEP_LOG_LINE@python.inline@  subprocess.check_call([adb_path, '-s', device, 'wait-for-device'])@@@",
       "@@@STEP_LOG_LINE@python.inline@  print 'Finished rooting device %s' % (device)@@@",
       "@@@STEP_LOG_END@python.inline@@@"
     ]
   },
   {
     "cmd": [
       "[BUILD]/scripts/slave/daemonizer.py",
       "--",
       "[SLAVE_BUILD]/src/build/android/adb_logcat_monitor.py",
-      "[SLAVE_BUILD]/src/out/logcat"
+      "[SLAVE_BUILD]/src/out/logcat_dir"
     ],
     "cwd": "[SLAVE_BUILD]",
     "env": {
       "PATH": "[SLAVE_BUILD]/src/third_party/android_tools/sdk/platform-tools:[SLAVE_BUILD]/src/build/android:%(PATH)s"
     },
     "name": "spawn_logcat_monitor"
   },
   {
     "cmd": [
       "python",
@@ skipping 424 matching lines @@
       "[TMP_BASE]/perf_archives_tmp_1/output_dir.zip",
       "gs://archives-bucket/perf_runner/perf_test.foo/20150928T110712_build_571.zip"
     ],
     "cwd": "[SLAVE_BUILD]",
     "name": "gsutil upload perf_test.foo output dir archive",
     "~followup_annotations": [
       "@@@STEP_LINK@output_dir.zip@https://storage.cloud.google.com/archives-bucket/perf_runner/perf_test.foo/20150928T110712_build_571.zip@@@"
     ]
   },
   {
+    "cmd": [],
+    "cwd": "[SLAVE_BUILD]",
+    "name": "AndroidWebViewTest"
+  },
+  {
+    "cmd": [
+      "[BUILD]/scripts/slave/daemonizer.py",
+      "--",
+      "[SLAVE_BUILD]/src/build/android/adb_logcat_monitor.py",
+      "[TMP_BASE]/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": "AndroidWebViewTest.spawn_logcat_monitor",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
     "cmd": [
       "[SLAVE_BUILD]/src/build/android/adb_install_apk.py",
       "[SLAVE_BUILD]/src/out/Release/apks/AndroidWebView.apk",
       "-v",
       "--blacklist-file",
       "[SLAVE_BUILD]/src/out/bad_devices.json",
       "--release"
     ],
     "cwd": "[SLAVE_BUILD]",
     "env": {
       "PATH": "[SLAVE_BUILD]/src/third_party/android_tools/sdk/platform-tools:[SLAVE_BUILD]/src/build/android:%(PATH)s"
     },
-    "name": "install AndroidWebView.apk"
+    "name": "AndroidWebViewTest.install AndroidWebView.apk",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
   },
   {
     "cmd": [
       "python",
       "-u",
       "[SLAVE_BUILD]/src/build/android/test_runner.py",
       "instrumentation",
       "--test-apk",
       "[SLAVE_BUILD]/src/out/Release/apks/AndroidWebViewTest.apk",
       "--blacklist-file",
       "[SLAVE_BUILD]/src/out/bad_devices.json",
       "--apk-under-test",
       "[SLAVE_BUILD]/src/out/Release/apks/AndroidWebView.apk",
       "--isolate-file-path",
       "android_webview/android_webview_test_apk.isolate",
       "--flakiness-dashboard-server",
       "test-results.appspot.com",
       "-A",
       "SmallTest",
       "-E",
       "FlakyTest",
       "--screenshot",
       "--release",
       "--host-driven-root",
       "[SLAVE_BUILD]/src/chrome/test",
       "--official-build"
     ],
     "cwd": "[SLAVE_BUILD]",
-    "name": "Instrumentation test SmallTest"
+    "name": "AndroidWebViewTest.Instrumentation test SmallTest",
+    "~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]/logcat_tmp_2"
+    ],
+    "cwd": "[SLAVE_BUILD]",
+    "name": "AndroidWebViewTest.logcat_dump",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [],
+    "cwd": "[SLAVE_BUILD]",
+    "name": "unittests"
+  },
+  {
+    "cmd": [
+      "[BUILD]/scripts/slave/daemonizer.py",
+      "--",
+      "[SLAVE_BUILD]/src/build/android/adb_logcat_monitor.py",
+      "[TMP_BASE]/logcat_tmp_3"
+    ],
+    "cwd": "[SLAVE_BUILD]",
+    "env": {
+      "PATH": "[SLAVE_BUILD]/src/third_party/android_tools/sdk/platform-tools:[SLAVE_BUILD]/src/build/android:%(PATH)s"
+    },
+    "name": "unittests.spawn_logcat_monitor",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [
       "python",
       "-u",
       "[SLAVE_BUILD]/src/build/android/test_runner.py",
       "gtest",
       "-s",
       "unittests",
       "--blacklist-file",
       "[SLAVE_BUILD]/src/out/bad_devices.json",
       "--verbose",
       "--release",
       "--isolate_file_path=[SLAVE_BUILD]/src/some_file.isolate",
       "--gtest_filter=WebRtc*",
       "--tool=asan"
     ],
     "cwd": "[SLAVE_BUILD]",
     "env": {
       "PATH": "[SLAVE_BUILD]/src/third_party/android_tools/sdk/platform-tools:[SLAVE_BUILD]/src/build/android:%(PATH)s"
     },
-    "name": "unittests"
+    "name": "unittests.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]/logcat_tmp_3"
+    ],
+    "cwd": "[SLAVE_BUILD]",
+    "name": "unittests.logcat_dump",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [
       "[SLAVE_BUILD]/src/tools/prepare-bisect-perf-regression.py",
       "-w",
       "[SLAVE_BUILD]"
     ],
     "cwd": "[SLAVE_BUILD]",
     "name": "prepare bisect perf regression"
   },
   {
     "cmd": [
       "[SLAVE_BUILD]/src/tools/run-bisect-perf-regression.py",
       "-w",
       "[SLAVE_BUILD]",
       "--extra_src",
       "test.py",
       "--path_to_config",
       "test.py"
     ],
     "cwd": "[SLAVE_BUILD]",
     "name": "run bisect perf regression"
   },
   {
     "cmd": [
       "python",
       "-u",
       "[BUILD]/scripts/slave/tee.py",
-      "[SLAVE_BUILD]/src/out/Release/full_log",
+      "[SLAVE_BUILD]/src/out/Release/full_logcat",
       "--",
       "[SLAVE_BUILD]/src/build/android/adb_logcat_printer.py",
-      "[SLAVE_BUILD]/src/out/logcat"
+      "[SLAVE_BUILD]/src/out/logcat_dir"
     ],
     "cwd": "[SLAVE_BUILD]",
     "name": "logcat_dump"
   },
   {
     "cmd": [
       "[SLAVE_BUILD]/src/third_party/android_platform/development/scripts/stack",
       "--arch",
       "arm",
       "--more-info",
-      "[SLAVE_BUILD]/src/out/Release/full_log"
+      "[SLAVE_BUILD]/src/out/Release/full_logcat"
     ],
     "cwd": "[SLAVE_BUILD]",
     "env": {
       "PATH": "[SLAVE_BUILD]/src/third_party/android_tools/sdk/platform-tools:[SLAVE_BUILD]/src/build/android:%(PATH)s"
     },
     "name": "stack_tool_with_logcat_dump"
   },
   {
     "cmd": [
       "[SLAVE_BUILD]/src/build/android/tombstones.py",
       "-a",
       "-s",
       "-w"
     ],
     "cwd": "[SLAVE_BUILD]",
     "env": {
       "PATH": "[SLAVE_BUILD]/src/third_party/android_tools/sdk/platform-tools:[SLAVE_BUILD]/src/build/android:%(PATH)s"
     },
     "name": "stack_tool_for_tombstones"
   },
   {
     "cmd": [
       "[SLAVE_BUILD]/src/build/android/asan_symbolize.py",
       "-l",
-      "[SLAVE_BUILD]/src/out/Release/full_log"
+      "[SLAVE_BUILD]/src/out/Release/full_logcat"
     ],
     "cwd": "[SLAVE_BUILD]",
     "env": {
       "PATH": "[SLAVE_BUILD]/src/third_party/android_tools/sdk/platform-tools:[SLAVE_BUILD]/src/build/android:%(PATH)s"
     },
     "name": "stack_tool_for_asan"
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]