Variations seed is pulled from the Java application on the first launch of Chrome

chrome/android/java/src/org/chromium/chrome/browser/preferences/PrefServiceBridge.java

Index: chrome/android/java/src/org/chromium/chrome/browser/preferences/PrefServiceBridge.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/preferences/PrefServiceBridge.java b/chrome/android/java/src/org/chromium/chrome/browser/preferences/PrefServiceBridge.java
index c5c1564f934cc2c01e0cd420b0881b04861c3966..f4142be5f6b87f200dd40c07733ed7e06999b38c 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/preferences/PrefServiceBridge.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/preferences/PrefServiceBridge.java
@@ -7,6 +7,7 @@ package org.chromium.chrome.browser.preferences;
 import android.content.Context;
 import android.content.SharedPreferences;
 import android.preference.PreferenceManager;
+import android.util.Base64;
 import android.util.Log;
 
 import org.chromium.base.ThreadUtils;
@@ -219,6 +220,46 @@ public final class PrefServiceBridge {
         }
     }
 
+    // TODO(agulenko): Move this piece of code to a separate class.

[newt (away), 2015/11/04 18:10:43]

Please remember to do this soon (put it on your personal TODO list). It's all
too common that promised follow-up work is quickly forgotten and someone else is
left to deal with the mess. I'm not saying that *you* would do this... but many
people do. Thank you :)

[Alexander Agulenko, 2015/11/05 00:44:21]

Acknowledged.

+
+    private static final String VARIATIONS_FIRST_RUN_SEED = "variations_seed";
+    private static final String VARIATIONS_FIRST_RUN_SEED_SIGNATURE = "variations_seed_signature";
+    private static final String VARIATIONS_FIRST_RUN_SEED_COUNTRY = "variations_seed_country";
+
+    private static String getVariationsFirstRunSeedPref(Context context, String prefName) {
+        SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
+        return prefs.getString(prefName, new String());

[newt (away), 2015/11/04 18:10:43]

s/new String()/""/

(no need to allocate a new String, when "" is available)

[Alexander Agulenko, 2015/11/05 00:44:22]

Done.

+    }
+
+    private static void setVariationsFirstRunSeedPref(
+            Context context, String prefName, String data) {
+        SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
+        prefs.edit().putString(prefName, data).apply();
+    }
+
+    public static void setVariationsFirstRunSeed(
+            Context context, byte[] rawSeed, String signature, String country) {
+        setVariationsFirstRunSeedPref(

[newt (away), 2015/11/04 18:10:43]

write this as:

  SharedPreferences prefs =
PreferenceManager.getDefaultSharedPreferences(context);
  prefs.edit()
          .putString(VARIATIONS_FIRST_RUN_SEED, Base64.encodeToString(...))
          .putString(VARIATIONS_FIRST_RUN_SEED_SIGNATURE, signature)
          .putString(VARIATIONS_FIRST_RUN_SEED_COUNTRY, country)
          .apply();

That's more efficient that getting the default shared preferences object three
times and making three separate updates to it. It's also less code: you can
delete setVariationsFirstRunSeedPref().

[Alexander Agulenko, 2015/11/05 00:44:22]

Done.

+                context, VARIATIONS_FIRST_RUN_SEED, Base64.encodeToString(rawSeed, Base64.NO_WRAP));
+        setVariationsFirstRunSeedPref(context, VARIATIONS_FIRST_RUN_SEED_SIGNATURE, signature);
+        setVariationsFirstRunSeedPref(context, VARIATIONS_FIRST_RUN_SEED_COUNTRY, country);
+    }
+
+    @CalledByNative
+    private static String getVariationsFirstRunSeedData(Context context) {

[newt (away), 2015/11/04 18:10:43]

Do the base64 decoding here (in Java), and change the return value to byte[].
That minimizes the amount of code that cares how the rawSeed was stored in
shared prefs. (and it's probably faster because it eliminates the JNI string
conversion using ConvertJavaStringToUTF8())

This will also avoid issues between different base64 encoding/decoding settings.
E.g. some encoders append ='s to the end of the string to make the string length
a multiple of four; some decoders will fail if these equal signs aren't present
(some could fail if ='s are present).

[Alexander Agulenko, 2015/11/05 00:44:22]

Done.

+        return getVariationsFirstRunSeedPref(context, VARIATIONS_FIRST_RUN_SEED);
+    }
+
+    @CalledByNative
+    private static String getVariationsFirstRunSeedSignature(Context context) {
+        return getVariationsFirstRunSeedPref(context, VARIATIONS_FIRST_RUN_SEED_SIGNATURE);
+    }
+
+    @CalledByNative
+    private static String getVariationsFirstRunSeedCountry(Context context) {
+        return getVariationsFirstRunSeedPref(context, VARIATIONS_FIRST_RUN_SEED_COUNTRY);
+    }
+
     public boolean isAcceptCookiesEnabled() {
         return nativeGetAcceptCookiesEnabled();
     }