Bug 1078029 - Dispatch a dummy mouse event so that browser.js can pick up the event's retargeted target. r=wesj

dom/interfaces/base/nsIDOMWindowUtils.idl

@@ -261,7 +261,7 @@ interface nsIDOMWindowUtils : nsISupports {
 
   /** Synthesize a mouse event. The event types supported are:
    *    mousedown, mouseup, mousemove, mouseover, mouseout, contextmenu,
-   *    MozMouseHitTest
+   *    MozMouseHittest
    *
    * Events are sent in coordinates offset by aX and aY from the window.
    *

mobile/android/chrome/content/browser.js

@@ -4851,6 +4851,7 @@ var BrowserEventHandler = {
 
     BrowserApp.deck.addEventListener("DOMUpdatePageReport", PopupBlockerObserver.onUpdatePageReport, false);
     BrowserApp.deck.addEventListener("touchstart", this, true);
+    BrowserApp.deck.addEventListener("MozMouseHittest", this, true);
     BrowserApp.deck.addEventListener("click", InputWidgetHelper, true);
     BrowserApp.deck.addEventListener("click", SelectHelper, true);
 
@@ -4883,6 +4884,9 @@ var BrowserEventHandler = {
       case 'touchstart':
         this._handleTouchStart(aEvent);
         break;
+      case 'MozMouseHittest':
+        this._handleRetargetedTouchStart(aEvent);
+        break;
       case 'MozMagnifyGesture':
         this.observe(this, aEvent.type,
                      JSON.stringify({x: aEvent.screenX, y: aEvent.screenY,
@@ -4915,6 +4919,19 @@ var BrowserEventHandler = {
         Messaging.sendRequest({ type: "Panning:Override" });
       }
     }
+  },
+
+  _handleRetargetedTouchStart: function(aEvent) {
+    // we should only get this called just after a new touchstart with a single
+    // touch point.
+    if (!BrowserApp.isBrowserContentDocumentDisplayed() || aEvent.defaultPrevented) {
+      return;
+    }
+
+    let target = aEvent.target;
+    if (!target) {
+      return;
+    }
 
     let uri = this._getLinkURI(target);
     if (uri) {

widget/android/nsWindow.cpp

@@ -1088,6 +1088,19 @@ bool nsWindow::OnMultitouchEvent(AndroidGeckoEvent *ae)
         isDownEvent = (event.message == NS_TOUCH_START);
     }
 
+    if (isDownEvent && event.touches.Length() == 1) {
+        // Since touch events don't get retargeted by PositionedEventTargeting.cpp
+        // code on Fennec, we dispatch a dummy mouse event that *does* get
+        // retargeted. The Fennec browser.js code can use this to activate the
+        // highlight element in case the this touchstart is the start of a tap.
+        WidgetMouseEvent hittest(true, NS_MOUSE_MOZHITTEST, this, WidgetMouseEvent::eReal);
+        hittest.refPoint = LayoutDeviceIntPoint::FromUntyped(event.touches[0]->mRefPoint);
+        hittest.ignoreRootScrollFrame = true;
+        hittest.inputSource = nsIDOMMouseEvent::MOZ_SOURCE_TOUCH;
+        nsEventStatus status;
+        DispatchEvent(&hittest, status);
+    }
+
     // if the last event we got was a down event, then by now we know for sure whether
     // this block has been default-prevented or not. if we haven't already sent the
     // notification for this block, do so now.