Bug 971462 - Hide event type from constructor of WidgetCommandEvent r=smaug

The constructor of WidgetCommandEvent takes 2 nsAtom pointers.  One is for
specifying event type, the other is for specifying the command.  The
difference of these arguments are pretty unclear for other developers and
the former argument is always nsGkAtoms::onAppCommand unless nullptr in
C++ code.  So, we can hide the former argument.

Then, we should create another constructor for creating empty command event
from constructor of dom::CommandEvent.

Differential Revision: https://phabricator.services.mozilla.com/D2506

--HG--
extra : moz-landing-system : lando

dom/events/CommandEvent.cpp

@@ -15,8 +15,7 @@ CommandEvent::CommandEvent(EventTarget* aOwner,
                            nsPresContext* aPresContext,
                            WidgetCommandEvent* aEvent)
   : Event(aOwner, aPresContext,
-          aEvent ? aEvent :
-                   new WidgetCommandEvent(false, nullptr, nullptr, nullptr))
+          aEvent ? aEvent : new WidgetCommandEvent())
 {
   mEvent->mTime = PR_Now();
   if (aEvent) {

widget/MiscEvents.h

@@ -11,6 +11,7 @@
 #include "mozilla/BasicEvents.h"
 #include "nsCOMPtr.h"
 #include "nsAtom.h"
+#include "nsGkAtoms.h"
 #include "nsITransferable.h"
 
 namespace mozilla {
@@ -106,6 +107,7 @@ class WidgetCommandEvent : public WidgetGUIEvent
 public:
   virtual WidgetCommandEvent* AsCommandEvent() override { return this; }
 
+protected:
   WidgetCommandEvent(bool aIsTrusted, nsAtom* aEventType,
                      nsAtom* aCommand, nsIWidget* aWidget)
     : WidgetGUIEvent(aIsTrusted, eUnidentifiedEvent, aWidget,
@@ -115,6 +117,25 @@ public:
     mSpecifiedEventType = aEventType;
   }
 
+public:
+  /**
+   * Constructor to initialize an app command.  This is the only case to
+   * initialize this class as a command in C++ stack.
+   */
+  WidgetCommandEvent(bool aIsTrusted, nsAtom* aCommand, nsIWidget* aWidget)
+    : WidgetCommandEvent(aIsTrusted, nsGkAtoms::onAppCommand,
+                         aCommand, aWidget)
+  {
+  }
+
+  /**
+   * Constructor to initialize as internal event of dom::CommandEvent.
+   */
+  WidgetCommandEvent()
+    : WidgetCommandEvent(false, nullptr, nullptr, nullptr)
+  {
+  }
+
   virtual WidgetEvent* Duplicate() const override
   {
     MOZ_ASSERT(mClass == eCommandEventClass,

widget/gtk/nsWindow.cpp

@@ -2933,8 +2933,8 @@ bool
 nsWindow::DispatchCommandEvent(nsAtom* aCommand)
 {
     nsEventStatus status;
-    WidgetCommandEvent event(true, nsGkAtoms::onAppCommand, aCommand, this);
-    DispatchEvent(&event, status);
+    WidgetCommandEvent appCommandEvent(true, aCommand, this);
+    DispatchEvent(&appCommandEvent, status);
     return TRUE;
 }
 

widget/windows/KeyboardLayout.cpp

@@ -2146,16 +2146,17 @@ NativeKey::DispatchCommandEvent(uint32_t aEventCommand) const
          "event", this));
       return false;
   }
-  WidgetCommandEvent commandEvent(true, nsGkAtoms::onAppCommand,
-                                  command, mWidget);
+  WidgetCommandEvent appCommandEvent(true, command, mWidget);
 
-  mWidget->InitEvent(commandEvent);
+  mWidget->InitEvent(appCommandEvent);
   MOZ_LOG(sNativeKeyLogger, LogLevel::Info,
-    ("%p   NativeKey::DispatchCommandEvent(), dispatching %s command event...",
+    ("%p   NativeKey::DispatchCommandEvent(), dispatching "
+     "%s app command event...",
      this, nsAtomCString(command).get()));
-  bool ok = mWidget->DispatchWindowEvent(&commandEvent) || mWidget->Destroyed();
+  bool ok =
+    mWidget->DispatchWindowEvent(&appCommandEvent) || mWidget->Destroyed();
   MOZ_LOG(sNativeKeyLogger, LogLevel::Info,
-    ("%p   NativeKey::DispatchCommandEvent(), dispatched command event, "
+    ("%p   NativeKey::DispatchCommandEvent(), dispatched app command event, "
      "result=%s, mWidget->Destroyed()=%s",
      this, GetBoolName(ok), GetBoolName(mWidget->Destroyed())));
   return ok;

widget/windows/WinMouseScrollHandler.cpp

@@ -1415,10 +1415,10 @@ MouseScrollHandler::Device::Elantech::HandleKeyMessage(nsWindowBase* aWidget,
          "%s command event",
          aWParam == VK_NEXT ? "Forward" : "Back"));
 
-      WidgetCommandEvent commandEvent(true, nsGkAtoms::onAppCommand,
+      WidgetCommandEvent appCommandEvent(true,
         (aWParam == VK_NEXT) ? nsGkAtoms::Forward : nsGkAtoms::Back, aWidget);
-      InitEvent(aWidget, commandEvent);
-      aWidget->DispatchWindowEvent(&commandEvent);
+      InitEvent(aWidget, appCommandEvent);
+      aWidget->DispatchWindowEvent(&appCommandEvent);
     }
     else {
       MOZ_LOG(gMouseScrollLog, LogLevel::Info,