Moved androidID constant to a method

Summary:
androidID was a constant that was exposed as a Platform constant, but it seems to use slightly expensive methods when they need to be computed. Moving this to a method so that it is computed only when needed.
Test Plan

Reviewed By: ejanzer

Differential Revision: D6563853

fbshipit-source-id: 3c5929fcbc947c13c3a25f2bf473e145ac4bf73e

ReactAndroid/src/main/java/com/facebook/react/modules/systeminfo/AndroidInfoModule.java

@@ -15,6 +15,7 @@
 import com.facebook.react.bridge.ReactApplicationContext;
 import com.facebook.react.bridge.ReactContextBaseJavaModule;
 import com.facebook.react.common.build.ReactBuildConfig;
+import com.facebook.react.bridge.ReactMethod;
 import com.facebook.react.module.annotations.ReactModule;
 
 import java.util.HashMap;
@@ -76,7 +77,11 @@ public String getName() {
     constants.put("isTesting", "true".equals(System.getProperty(IS_TESTING)));
     constants.put("reactNativeVersion", ReactNativeVersion.VERSION);
     constants.put("uiMode", uiMode());
-    constants.put("androidID", Secure.getString(getReactApplicationContext().getContentResolver(), Secure.ANDROID_ID));
     return constants;
   }
+
+  @ReactMethod(isBlockingSynchronousMethod = true)
+  public String getAndroidID(){
+    return Secure.getString(getReactApplicationContext().getContentResolver(),Secure.ANDROID_ID);
+  }
 }