Fix blank initial pages when the WebView is (re)created

This basically does a refresh call when the HTML is loaded and the
container is first initialised. If the container wasn't ready when a
"display content" call came in, then it ends up loading it here

It's *possible* that some content might refresh the display twice, if
the container initialised refresh coincides with the app setting the
content, so there are two JS #showPageHtml calls after bodyHtml is set.
I'm only mentioning it in case it comes up as a "why's that happening"
issue - it should be rare if it ever happens, and it would only be a
single glitch when the WebView is first initialised

Fixes #653

Awful.apk/src/main/assets/javascript/thread.js

@@ -83,6 +83,9 @@ function containerInit() {
 	window.addEventListener('awful-scroll-post', function scrollToPost() {
 		window.topScrollID = window.requestAnimationFrame(scrollPost.bind(null, null));
 	});
+
+    // trigger a page content load, in case some was sent before the container was ready to handle it
+    loadPageHtml();
 }
 
 /**

Awful.apk/src/main/java/com/ferg/awfulapp/webview/WebViewJsInterface.java

@@ -2,8 +2,6 @@
 
 import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
-import android.support.annotation.WorkerThread;
-import android.util.Log;
 import android.webkit.JavascriptInterface;
 
 import com.ferg.awfulapp.preferences.AwfulPreferences;
@@ -12,6 +10,8 @@
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 
+import timber.log.Timber;
+
 /**
  * Created by baka kaba on 23/01/2017.
  * <p>
@@ -21,27 +21,17 @@
  * be used in a {@link com.ferg.awfulapp.ThreadDisplayFragment} and needs to react to other UI clicks.
  */
 // TODO: 12/02/2017 JS interface methods are called on a separate thread apparently - none of our implementations are thread-safe at all
-@WorkerThread
 public class WebViewJsInterface {
 
-    private static final String TAG = "WebViewJsInterface";
-
     private final Map<String, String> preferences = new ConcurrentHashMap<>();
 
     @NonNull
-    private String bodyHtml = "";
-
-    @Nullable
-    private AwfulWebView webView = null;
+    private volatile String bodyHtml = "";
 
     public WebViewJsInterface() {
         updatePreferences();
     }
 
-    void setWebView(@NonNull AwfulWebView webView) {
-        this.webView = webView;
-    }
-
     /**
      * Updates the JavaScript-accessible preference store from the current values in AwfulPreferences.
      */
@@ -77,8 +67,6 @@ public final void updatePreferences() {
     protected void setCustomPreferences(Map<String, String> preferences) {
     }
 
-    // TODO: sync for threads? check html -> update html needs to be atomic?
-
     @NonNull
     @JavascriptInterface
     public final String getBodyHtml() {
@@ -97,7 +85,7 @@ public String getPreference(String preference) {
 
     @JavascriptInterface
     public void debugMessage(final String msg) {
-        Log.d(TAG, "Awful DEBUG: " + msg);
+        Timber.d("Awful DEBUG: %s", msg);
     }
 
     // TODO: 28/01/2017 work out if any other common interface methods can go in here