Bug 1367081 - Make PromptService usable from GeckoView custom tabs; r=droeh

Make PromptService and Prompt.jsm not depend as much on BrowserApp and
the main Fennec window, so it can be used from a GeckoView-based custom
tabs Activity. This approach is used because it involves a lot less work
than trying to implement a PromptDelegate for Fennec.

MozReview-Commit-ID: AEH0HgAOx2S

mobile/android/base/java/org/mozilla/gecko/GeckoApp.java

@@ -1841,7 +1841,7 @@ public abstract class GeckoApp extends GeckoActivity
             startActivity(settingsIntent);
         }
 
-        mPromptService = new PromptService(this);
+        mPromptService = new PromptService(this, getAppEventDispatcher());
 
         // Trigger the completion of the telemetry timer that wraps activity startup,
         // then grab the duration to give to FHR.

mobile/android/base/java/org/mozilla/gecko/prompts/PromptService.java

@@ -6,8 +6,6 @@
 package org.mozilla.gecko.prompts;
 
 import org.mozilla.gecko.EventDispatcher;
-import org.mozilla.gecko.GeckoApp;
-import org.mozilla.gecko.GeckoAppShell;
 import org.mozilla.gecko.util.BundleEventListener;
 import org.mozilla.gecko.util.EventCallback;
 import org.mozilla.gecko.util.GeckoBundle;
@@ -19,17 +17,19 @@ import android.util.Log;
 public class PromptService implements BundleEventListener {
     private static final String LOGTAG = "GeckoPromptService";
 
-    private final GeckoApp mGeckoApp;
+    private final Context mContext;
+    private final EventDispatcher mDispatcher;
 
-    public PromptService(GeckoApp geckoApp) {
-        mGeckoApp = geckoApp;
-        mGeckoApp.getAppEventDispatcher().registerUiThreadListener(this,
+    public PromptService(final Context context, final EventDispatcher dispatcher) {
+        mContext = context;
+        mDispatcher = dispatcher;
+        mDispatcher.registerUiThreadListener(this,
             "Prompt:Show",
             "Prompt:ShowTop");
     }
 
     public void destroy() {
-        mGeckoApp.getAppEventDispatcher().unregisterUiThreadListener(this,
+        mDispatcher.unregisterUiThreadListener(this,
             "Prompt:Show",
             "Prompt:ShowTop");
     }
@@ -39,7 +39,7 @@ public class PromptService implements BundleEventListener {
     public void handleMessage(final String event, final GeckoBundle message,
                               final EventCallback callback) {
         Prompt p;
-        p = new Prompt(mGeckoApp, new Prompt.PromptCallback() {
+        p = new Prompt(mContext, new Prompt.PromptCallback() {
             @Override
             public void onPromptFinished(final GeckoBundle result) {
                 callback.sendSuccess(result);

mobile/android/modules/Prompt.jsm

@@ -7,6 +7,7 @@
 var Cc = Components.classes;
 var Ci = Components.interfaces;
 
+Components.utils.import("resource://gre/modules/Messaging.jsm");
 Components.utils.import("resource://gre/modules/Services.jsm");
 
 this.EXPORTED_SYMBOLS = ["Prompt"];
@@ -15,14 +16,24 @@ function log(msg) {
   Services.console.logStringMessage(msg);
 }
 
+function getRootWindow(win) {
+  // Get the root xul window.
+  return win.QueryInterface(Ci.nsIInterfaceRequestor)
+            .getInterface(Ci.nsIDocShell).QueryInterface(Ci.nsIDocShellTreeItem)
+            .rootTreeItem.QueryInterface(Ci.nsIInterfaceRequestor)
+            .getInterface(Ci.nsIDOMWindow);
+}
+
 function Prompt(aOptions) {
   this.window = "window" in aOptions ? aOptions.window : null;
 
   this.msg = { async: true };
 
   if (this.window) {
-    let window = Services.wm.getMostRecentWindow("navigator:browser");
-    var tab = window.BrowserApp.getTabForWindow(this.window);
+    let window = getRootWindow(this.window);
+    var tab = window &&
+              window.BrowserApp &&
+              window.BrowserApp.getTabForWindow(this.window);
     if (tab) {
       this.msg.tabId = tab.id;
     }
@@ -174,11 +185,24 @@ Prompt.prototype = {
     this._innerShow();
   },
 
+  _getDispatcher: function(win) {
+    let root = win && getRootWindow(win);
+    try {
+      return root && (root.WindowEventDispatcher || EventDispatcher.for(root));
+    } catch (e) {
+      // No EventDispatcher for this window.
+      return null;
+    }
+  },
+
   _innerShow: function() {
-    let window = Services.wm.getMostRecentWindow("navigator:browser");
-    window.WindowEventDispatcher.sendRequestForResult(this.msg).then((data) => {
-      if (this.callback)
+    let dispatcher =
+        this._getDispatcher(this.window) ||
+        this._getDispatcher(Services.wm.getMostRecentWindow("navigator:browser"));
+    dispatcher.sendRequestForResult(this.msg).then((data) => {
+      if (this.callback) {
         this.callback(data);
+      }
     });
   },