Register cct module lifecycle state in a synthetic field trial.

In the UMA dashboard we can use this to slice metrics like PrivateMemoryFootprint.

Bug: 882370
Change-Id: I70f07590db3ad183325ed2e4e03fbe680413c937
Reviewed-on: https://chromium-review.googlesource.com/c/1405189Reviewed-by: Anna Malova <amalova@chromium.org>
Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Commit-Queue: Michael van Ouwerkerk <mvanouwerkerk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#622056}

chrome/android/java/src/org/chromium/chrome/browser/customtabs/dynamicmodule/ModuleLoader.java

@@ -115,6 +115,8 @@ public class ModuleLoader {
             return;
         }
 
+        ModuleMetrics.registerLifecycleState(ModuleMetrics.LifecycleState.NOT_LOADED);
+
         mIsModuleLoading = true;
         new LoadClassTask(moduleContext).executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
     }
@@ -199,6 +201,7 @@ public class ModuleLoader {
         ModuleMetrics.recordDestruction(reason);
         mModuleEntryPoint.onDestroy();
         CrashKeys.getInstance().set(CrashKeyIndex.ACTIVE_DYNAMIC_MODULE, null);
+        ModuleMetrics.registerLifecycleState(ModuleMetrics.LifecycleState.DESTROYED);
         mModuleEntryPoint = null;
         mModuleUnusedTimeMs = -1;
     }
@@ -303,6 +306,8 @@ public class ModuleLoader {
                 crashKeys.set(CrashKeyIndex.LOADED_DYNAMIC_MODULE, mModuleId);
                 crashKeys.set(CrashKeyIndex.ACTIVE_DYNAMIC_MODULE, mModuleId);
 
+                ModuleMetrics.registerLifecycleState(ModuleMetrics.LifecycleState.INSTANTIATED);
+
                 long entryPointInitStartTime = ModuleMetrics.now();
                 entryPoint.init(moduleHost);
                 ModuleMetrics.recordEntryPointInitTime(entryPointInitStartTime);

chrome/android/java/src/org/chromium/chrome/browser/customtabs/dynamicmodule/ModuleMetrics.java

@@ -6,9 +6,11 @@ package org.chromium.chrome.browser.customtabs.dynamicmodule;
 
 import android.os.SystemClock;
 import android.support.annotation.IntDef;
+import android.support.annotation.StringDef;
 
 import org.chromium.base.Log;
 import org.chromium.base.metrics.RecordHistogram;
+import org.chromium.chrome.browser.metrics.UmaSessionStats;
 
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
@@ -22,6 +24,11 @@ public final class ModuleMetrics {
 
     private static final String TAG = "ModuleMetrics";
 
+    /**
+     * The name of the synthetic field trial for registering the module lifecycle state.
+     */
+    private static final String LIFECYCLE_STATE_TRIAL_NAME = "CCTModuleLifecycleState";
+
     /**
      * Possible results when loading a dynamic module. Keep in sync with the
      * CustomTabs.DynamicModule.LoadResult enum in histograms.xml. Do not remove
@@ -137,4 +144,25 @@ public final class ModuleMetrics {
                 "CustomTabs.DynamicModule.EntryPointInitTime", now() - startTime,
                 TimeUnit.MILLISECONDS);
     }
+
+    /**
+     * Possible lifecycle states for a dynamic module.
+     */
+    @StringDef({LifecycleState.NOT_LOADED, LifecycleState.INSTANTIATED, LifecycleState.DESTROYED})
+    public @interface LifecycleState {
+        /** The module has not yet been loaded. */
+        String NOT_LOADED = "NotLoaded";
+        /** The module has been loaded and instantiated. */
+        String INSTANTIATED = "Instantiated";
+        /** The module instance has been destroyed. */
+        String DESTROYED = "Destroyed";
+    }
+
+    /**
+     * Registers the module lifecycle state in a synthetic field trial.
+     * @param state The module lifecycle state.
+     */
+    public static void registerLifecycleState(@LifecycleState String state) {
+        UmaSessionStats.registerSyntheticFieldTrial(LIFECYCLE_STATE_TRIAL_NAME, state);
+    }
 }