[Herb] Set up field trial for UI prototypes

chrome/android/java/src/org/chromium/chrome/browser/util/FeatureUtilities.java

Index: chrome/android/java/src/org/chromium/chrome/browser/util/FeatureUtilities.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/util/FeatureUtilities.java b/chrome/android/java/src/org/chromium/chrome/browser/util/FeatureUtilities.java
index 2089a3bc9ad737432c59f35c72ed42cf48fd8fc8..8742ff0dc17ccab075fc86f8c98fa846626bcb12 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/util/FeatureUtilities.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/util/FeatureUtilities.java
@@ -12,14 +12,21 @@ import android.content.pm.PackageManager;
 import android.content.pm.ResolveInfo;
 import android.os.Build;
 import android.os.Bundle;
+import android.os.StrictMode;
 import android.os.UserManager;
 import android.speech.RecognizerIntent;
+import android.text.TextUtils;
 
+import org.chromium.base.ApplicationStatus;
 import org.chromium.base.CommandLine;
+import org.chromium.base.Log;
 import org.chromium.base.ThreadUtils;
 import org.chromium.base.VisibleForTesting;
 import org.chromium.chrome.browser.ChromeSwitches;
+import org.chromium.chrome.browser.ChromeVersionInfo;
+import org.chromium.chrome.browser.preferences.ChromePreferenceManager;
 import org.chromium.chrome.browser.preferences.DocumentModeManager;
+import org.chromium.components.variations.VariationsAssociatedData;
 import org.chromium.sync.signin.AccountManagerHelper;
 import org.chromium.ui.base.DeviceFormFactor;
 
@@ -30,9 +37,17 @@ import java.util.List;
  * this device.
  */
 public class FeatureUtilities {
+    private static final String TAG = "FeatureUtilities";
+    private static final String HERB_EXPERIMENT_NAME = "TabManagementExperiment";
+    private static final String HERB_EXPERIMENT_FLAVOR_PARAM = "type";
+
     private static Boolean sHasGoogleAccountAuthenticator;
     private static Boolean sHasRecognitionIntentHandler;
     private static Boolean sDocumentModeDisabled;
+
+    private static String sCachedHerbFlavor;
+    private static boolean sIsHerbFlavorCached;
+
     /** Used to track if cached command line flags should be refreshed. */
     private static CommandLine.ResetListener sResetListener = null;
 
@@ -171,6 +186,60 @@ public class FeatureUtilities {
         CommandLine.addResetListener(sResetListener);
     }
 
+    /**
+     * @return Which flavor of Herb is active, or null if a prototype isn't being tested.
+     */
+    public static String getHerbFlavor() {
+        if (!sIsHerbFlavorCached) {
+            Context context = ApplicationStatus.getApplicationContext();
+            if (isDocumentMode(context)) return null;
+            if (ChromeVersionInfo.isStableBuild() || ChromeVersionInfo.isBetaBuild()) return null;
+            if (DeviceFormFactor.isTablet(context)) return null;
+
+            // Allowing disk access for preferences while prototyping.
+            sCachedHerbFlavor = null;
+            StrictMode.ThreadPolicy oldPolicy = StrictMode.allowThreadDiskReads();
+            try {
+                sCachedHerbFlavor =
+                        ChromePreferenceManager.getInstance(context).getCachedHerbFlavor();
+            } finally {
+                StrictMode.setThreadPolicy(oldPolicy);
+            }
+
+            sIsHerbFlavorCached = true;
+            Log.d(TAG, "Retrieved cached Herb flavor: " + sCachedHerbFlavor);
+        }
+
+        return sCachedHerbFlavor;
+    }
+
+    /**
+     * Caches which flavor of Herb the user prefers from native.
+     */
+    public static void cacheHerbFlavor() {
+        String oldFlavor = getHerbFlavor();
+        String newFlavor = null;
+
+        // Check the experiment value before the command line.
+        String experimentValue = VariationsAssociatedData.getVariationParamValue(
+                HERB_EXPERIMENT_NAME, HERB_EXPERIMENT_FLAVOR_PARAM);
+
+        newFlavor = CommandLine.getInstance().getSwitchValue(ChromeSwitches.HERB_FLAVOR, null);
+        if (TextUtils.isEmpty(newFlavor)) {
+            Log.d(TAG, "Caching flavor from experiment: " + experimentValue);
+            newFlavor = experimentValue;
+        } else {
+            Log.d(TAG, "Caching flavor from command line: " + newFlavor);
+        }
+
+        sCachedHerbFlavor = newFlavor;
+
+        if (!TextUtils.equals(oldFlavor, newFlavor)) {
+            Context context = ApplicationStatus.getApplicationContext();
+            ChromePreferenceManager.getInstance(context).setCachedHerbFlavor(newFlavor);
+        }
+    }
+
     private static native void nativeSetDocumentModeEnabled(boolean enabled);
     private static native void nativeSetCustomTabVisible(boolean visible);
     public static native void nativeSetSqlMmapDisabledByDefault();