Add per-action instrumentation for UX performance

- Implement a new Marker API in BaseUiAutomation so workload can
  generate start and end markers with string name. Outputs to logcat.

- Document the Marker output log format in the WA documentation

- Create a results processor to take existing instrument fps logs and
  parse them based on the workload markers. Produce per-action fps
  metrics.

- Add simple timing results based on the workload markers

wlauto/external/uiauto/src/com/arm/wlauto/uiauto/BaseUiAutomation.java

@@ -27,6 +27,7 @@ import java.util.regex.Pattern;
 
 import android.app.Activity;
 import android.os.Bundle;
+import android.util.Log;
 
 // Import the uiautomator libraries
 import com.android.uiautomator.core.UiObject;
@@ -37,6 +38,47 @@ import com.android.uiautomator.testrunner.UiAutomatorTestCase;
 
 public class BaseUiAutomation extends UiAutomatorTestCase {   
 
+    /**
+     * Basic marker API for workloads to generate start and end markers for
+     * deliminating and timing actions. Markers are output to logcat with debug
+     * priority. Actions represent a series of UI interactions to time.
+     *
+     * The marker API provides a way for instruments and result processors to hook into
+     * per-action timings by parsing logcat logs produced per workload iteration.
+     *
+     * The marker output consists of a logcat tag 'UX_PERF' and a message. The
+     * message consists of a name for the action and a timestamp. The timestamp
+     * is separated by a single space from the name of the action.
+     *
+     * Typical usage:
+     *
+     * ActionLogger logger = ActionLogger("testTag", parameters);
+     * logger.start();
+     * // actions to be recorded
+     * logger.stop();
+     */
+    public class ActionLogger {
+
+        private String testTag;
+        private boolean enabled;
+
+        public ActionLogger(String testTag, Bundle parameters) {
+            this.testTag = testTag;
+            this.enabled = Boolean.parseBoolean(parameters.getString("dumpsys_enabled"));
+        }
+
+        public void start() {
+            if (enabled) {
+                Log.d("UX_PERF", testTag + "_start " + System.nanoTime());
+            }
+        }
+
+        public void stop() throws Exception {
+            if (enabled) {
+                Log.d("UX_PERF", testTag + "_end " + System.nanoTime());
+            }
+        }
+    }
 
     public void sleep(int second) {
         super.sleep(second * 1000);