Fix java classes missing @MainDex.

base/android/java/src/org/chromium/base/ContextUtils.java

Index: base/android/java/src/org/chromium/base/ContextUtils.java
diff --git a/base/android/java/src/org/chromium/base/ContextUtils.java b/base/android/java/src/org/chromium/base/ContextUtils.java
index 4b615cb3ea93160c5d55ad37905335d1a64c17db..448eff9b6a9f33ebf3ef4c3eecaa91711bd7d0a1 100644
--- a/base/android/java/src/org/chromium/base/ContextUtils.java
+++ b/base/android/java/src/org/chromium/base/ContextUtils.java
@@ -9,11 +9,13 @@ import android.content.SharedPreferences;
 import android.preference.PreferenceManager;
 
 import org.chromium.base.annotations.JNINamespace;
+import org.chromium.base.annotations.MainDex;
 
 /**
  * This class provides Android application context related utility methods.
  */
 @JNINamespace("base::android")
+@MainDex
 public class ContextUtils {
     private static final String TAG = "ContextUtils";
     private static Context sApplicationContext;