Revert "Remove some unnecessary/dead code from TabChild."

The commit was not actually suitable for v38. It seems the
HasValidInnerSize function was moved from TabChildBase to TabChild
somewhere between v32 and v38.

This reverts commit a4eddcd.

embedding/embedlite/utils/TabChildHelper.cpp

@@ -51,6 +51,7 @@ static bool sPostAZPCAsJsonViewport(false);
 
 TabChildHelper::TabChildHelper(EmbedLiteViewChildIface* aView)
   : mView(aView)
+  , mHasValidInnerSize(false)
 {
   LOGT();
 
@@ -200,6 +201,12 @@ TabChildHelper::InitTabChildGlobal()
   return true;
 }
 
+bool
+TabChildHelper::HasValidInnerSize()
+{
+  return mHasValidInnerSize;
+}
+
 NS_IMETHODIMP
 TabChildHelper::Observe(nsISupports* aSubject,
                         const char* aTopic,

embedding/embedlite/utils/TabChildHelper.h

@@ -70,6 +70,7 @@ class TabChildHelper : public mozilla::dom::TabChildBase,
   bool ConvertMutiTouchInputToEvent(const mozilla::MultiTouchInput& aData,
                                     WidgetTouchEvent& aEvent);
   void CancelTapTracking();
+  bool HasValidInnerSize();
 
 private:
   bool InitTabChildGlobal();
@@ -81,6 +82,7 @@ class TabChildHelper : public mozilla::dom::TabChildBase,
   friend class EmbedLiteViewChildIface;
   friend class EmbedLiteViewBaseChild;
   EmbedLiteViewChildIface* mView;
+  bool mHasValidInnerSize;
 };
 
 }