First-cut at fixing unhandled Tap event returns in Blink.

Source/core/page/EventHandler.cpp

Index: Source/core/page/EventHandler.cpp
diff --git a/Source/core/page/EventHandler.cpp b/Source/core/page/EventHandler.cpp
index 2c57862dcc21a9a1e890935f48db0ffca70a537c..fbac989ba723daa141e95d86bf5f78b551331ecf 100644
--- a/Source/core/page/EventHandler.cpp
+++ b/Source/core/page/EventHandler.cpp
@@ -230,6 +230,7 @@ EventHandler::EventHandler(LocalFrame* frame)
     , m_longTapShouldInvokeContextMenu(false)
     , m_activeIntervalTimer(this, &EventHandler::activeIntervalTimerFired)
     , m_lastShowPressTimestamp(0)
+    , m_fixTapGestureReturnValue(false)
 {
 }
 
@@ -614,6 +615,8 @@ bool EventHandler::handleMousePressEvent(const MouseEventWithHitTestResults& eve
         swallowEvent = handleMousePressEventTripleClick(event);
     else
         swallowEvent = handleMousePressEventSingleClick(event);
+    if (m_fixTapGestureReturnValue)
+        swallowEvent = false;

[Rick Byers, 2014/05/16 11:10:43]

This seems wrong.  A click from touch is as legitimate as a click from mouse
(it's not "fake" - click really means activate and is sent for keyboard as
well).  So, for example, if a webpage calls preventDefault on click then you
should absolutely NOT be doing some extra browser UI in that case ("content not
chrome" - the app owns it's event stream first).

[Donn Denman, 2014/05/27 05:58:14]

Done.

 
     m_mouseDownMayStartAutoscroll = m_mouseDownMayStartSelect
         || (m_mousePressNode && m_mousePressNode->renderBox() && m_mousePressNode->renderBox()->canBeProgramaticallyScrolled());
@@ -2229,6 +2232,7 @@ bool EventHandler::handleGestureTap(const PlatformGestureEvent& gestureEvent, co
     handleMouseMoveEvent(fakeMouseMove);
 
     bool defaultPrevented = false;
+    m_fixTapGestureReturnValue = true;
     PlatformMouseEvent fakeMouseDown(adjustedPoint, gestureEvent.globalPosition(),
         LeftButton, PlatformEvent::MousePressed, gestureEvent.tapCount(),
         modifiers, PlatformMouseEvent::FromTouch,  gestureEvent.timestamp());
@@ -2238,6 +2242,8 @@ bool EventHandler::handleGestureTap(const PlatformGestureEvent& gestureEvent, co
         LeftButton, PlatformEvent::MouseReleased, gestureEvent.tapCount(),
         modifiers, PlatformMouseEvent::FromTouch,  gestureEvent.timestamp());
     defaultPrevented |= handleMouseReleaseEvent(fakeMouseUp);
+    // TODO(donnd): do we need to worry about exceptions being thrown above?
+    m_fixTapGestureReturnValue = false;
 
     return defaultPrevented;
 }