Bug 1153023 - Send the child process a dimensions update when the offset changes. r=roc

dom/ipc/TabParent.cpp

@@ -353,6 +353,10 @@ TabParent::AddWindowListeners()
                                       this, false, false);
       }
     }
+    if (nsIPresShell* shell = mFrameElement->OwnerDoc()->GetShell()) {
+      mPresShellWithRefreshListener = shell;
+      shell->AddPostRefreshObserver(this);
+    }
   }
 }
 
@@ -367,6 +371,18 @@ TabParent::RemoveWindowListeners()
                                        this, false);
     }
   }
+  if (mPresShellWithRefreshListener) {
+    mPresShellWithRefreshListener->RemovePostRefreshObserver(this);
+    mPresShellWithRefreshListener = nullptr;
+  }
+}
+
+void
+TabParent::DidRefresh()
+{
+  if (mChromeOffset != -GetChildProcessOffset()) {
+    UpdatePosition();
+  }
 }
 
 void
@@ -401,6 +417,8 @@ TabParent::Destroy()
     return;
   }
 
+  RemoveWindowListeners();
+
   // If this fails, it's most likely due to a content-process crash,
   // and auto-cleanup will kick in.  Otherwise, the child side will
   // destroy itself and send back __delete__().
@@ -910,6 +928,19 @@ TabParent::RecvSetDimensions(const uint32_t& aFlags,
   return false;
 }
 
+nsresult
+TabParent::UpdatePosition()
+{
+  nsRefPtr<nsFrameLoader> frameLoader = GetFrameLoader();
+  if (!frameLoader) {
+    return NS_OK;
+  }
+  nsIntRect windowDims;
+  NS_ENSURE_SUCCESS(frameLoader->GetWindowDimensions(windowDims), NS_ERROR_FAILURE);
+  UpdateDimensions(windowDims, mDimensions);
+  return NS_OK;
+}
+
 void
 TabParent::UpdateDimensions(const nsIntRect& rect, const ScreenIntSize& size)
 {
@@ -2997,14 +3028,7 @@ TabParent::HandleEvent(nsIDOMEvent* aEvent)
   if (eventType.EqualsLiteral("MozUpdateWindowPos") && !mIsDestroyed) {
     // This event is sent when the widget moved.  Therefore we only update
     // the position.
-    nsRefPtr<nsFrameLoader> frameLoader = GetFrameLoader();
-    if (!frameLoader) {
-      return NS_OK;
-    }
-    nsIntRect windowDims;
-    NS_ENSURE_SUCCESS(frameLoader->GetWindowDimensions(windowDims), NS_ERROR_FAILURE);
-    UpdateDimensions(windowDims, mDimensions);
-    return NS_OK;
+    return UpdatePosition();
   }
   return NS_OK;
 }

dom/ipc/TabParent.h

@@ -23,6 +23,7 @@
 #include "nsISecureBrowserUI.h"
 #include "nsITabParent.h"
 #include "nsIXULBrowserWindow.h"
+#include "nsRefreshDriver.h"
 #include "nsWeakReference.h"
 #include "Units.h"
 #include "nsIWidget.h"
@@ -74,6 +75,7 @@ class TabParent final : public PBrowserParent
                       , public nsISecureBrowserUI
                       , public nsSupportsWeakReference
                       , public TabContext
+                      , public nsAPostRefreshObserver
 {
     typedef mozilla::dom::ClonedMessageData ClonedMessageData;
 
@@ -120,6 +122,7 @@ public:
 
     void RemoveWindowListeners();
     void AddWindowListeners();
+    void DidRefresh() override;
 
     virtual bool RecvMoveFocus(const bool& aForward) override;
     virtual bool RecvEvent(const RemoteDOMEvent& aEvent) override;
@@ -488,6 +491,8 @@ private:
     nsRefPtr<nsIContentParent> mManager;
     void TryCacheDPIAndScale();
 
+    nsresult UpdatePosition();
+
     CSSPoint AdjustTapToChildWidget(const CSSPoint& aPoint);
 
     // Update state prior to routing an APZ-aware event to the child process.
@@ -596,6 +601,8 @@ private:
     // cursor.  This happens whenever the cursor is in the tab's region.
     bool mTabSetsCursor;
 
+    nsRefPtr<nsIPresShell> mPresShellWithRefreshListener;
+
 private:
     // This is used when APZ needs to find the TabParent associated with a layer
     // to dispatch events.