Enable asset tasks when using gradle to process resources.

build/android/gradle/android.jinja

Index: build/android/gradle/android.jinja
diff --git a/build/android/gradle/android.jinja b/build/android/gradle/android.jinja
index 385d999db0f0c940e28e0c1d4e25d35e3be4732c..513927c1e00aabdc8dd46e36c019a78778f663cd 100644
--- a/build/android/gradle/android.jinja
+++ b/build/android/gradle/android.jinja
@@ -77,7 +77,9 @@ afterEvaluate {
     def tasksToDisable = tasks.findAll {
         return (it.name.equals('generateDebugSources')  // causes unwanted AndroidManifest.java
                 || it.name.equals('generateReleaseSources')
+{% if not use_gradle_process_resources %}
                 || it.name.endsWith('Assets')
+{% endif %}
                 || it.name.endsWith('BuildConfig')  // causes unwanted BuildConfig.java
 {% if not use_gradle_process_resources %}
                 || it.name.endsWith('Resources')