Bug 1118169 - Support -moz-window-dragging:drag in HTML. r=mstange r=bz

docshell/base/nsDocShell.cpp

@@ -842,6 +842,7 @@ nsDocShell::nsDocShell():
     mInPrivateBrowsing(false),
     mUseRemoteTabs(false),
     mDeviceSizeIsPageSize(false),
+    mWindowDraggingAllowed(false),
     mCanExecuteScripts(false),
     mFiredUnloadEvent(false),
     mEODForCurrentDocument(false),
@@ -3013,6 +3014,35 @@ nsDocShell::AddProfileTimelineMarker(UniquePtr<TimelineMarker>& aMarker)
   }
 }
 
+NS_IMETHODIMP
+nsDocShell::SetWindowDraggingAllowed(bool aValue)
+{
+  nsRefPtr<nsDocShell> parent = GetParentDocshell();
+  if (!aValue && mItemType == typeChrome && !parent) {
+    // Window dragging is always allowed for top level
+    // chrome docshells.
+    return NS_ERROR_FAILURE;
+  }
+  mWindowDraggingAllowed = aValue;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDocShell::GetWindowDraggingAllowed(bool* aValue)
+{
+  // window dragging regions in CSS (-moz-window-drag:drag)
+  // can be slow. Default behavior is to only allow it for
+  // chrome top level windows.
+  nsRefPtr<nsDocShell> parent = GetParentDocshell();
+  if (mItemType == typeChrome && !parent) {
+    // Top level chrome window
+    *aValue = true;
+  } else {
+    *aValue = mWindowDraggingAllowed;
+  }
+  return NS_OK;
+}
+
 void
 nsDocShell::ClearProfileTimelineMarkers()
 {

docshell/base/nsDocShell.h

@@ -885,6 +885,7 @@ protected:
     bool                       mInPrivateBrowsing;
     bool                       mUseRemoteTabs;
     bool                       mDeviceSizeIsPageSize;
+    bool                       mWindowDraggingAllowed;
 
     // Because scriptability depends on the mAllowJavascript values of our
     // ancestors, we cache the effective scriptability and recompute it when

docshell/base/nsIDocShell.idl

@@ -54,7 +54,7 @@ interface nsITabParent;
  
 typedef unsigned long nsLoadFlags;
 
-[scriptable, builtinclass, uuid(e0e833fe-3a5b-48b0-8684-a097e09c0723)]
+[scriptable, builtinclass, uuid(888fcf04-a69b-11e4-8d33-6fbb72d2eb03)]
 interface nsIDocShell : nsIDocShellTreeItem
 {
   /**
@@ -1053,4 +1053,11 @@ interface nsIDocShell : nsIDocShellTreeItem
    * Holds the id of the payment request associated with this docshell if any.
    */
   attribute DOMString paymentRequestId;
+
+  /**
+   * Allow usage of -moz-window-dragging:drag for content docshells.
+   * True for top level chrome docshells. Throws if set to false with
+   * top level chrome docshell.
+   */
+  attribute boolean windowDraggingAllowed;
 };

layout/base/nsDisplayList.cpp

@@ -587,7 +587,8 @@ nsDisplayListBuilder::nsDisplayListBuilder(nsIFrame* aReferenceFrame,
       mContainsPluginItem(false),
       mAncestorHasTouchEventHandler(false),
       mAncestorHasScrollEventHandler(false),
-      mHaveScrollableDisplayPort(false)
+      mHaveScrollableDisplayPort(false),
+      mWindowDraggingAllowed(false)
 {
   MOZ_COUNT_CTOR(nsDisplayListBuilder);
   PL_InitArenaPool(&mPool, "displayListArena", 1024,
@@ -1002,6 +1003,9 @@ nsDisplayListBuilder::EnterPresShell(nsIFrame* aReferenceFrame)
     mFramesMarkedForDisplay.AppendElement(state->mCaretFrame);
     MarkFrameForDisplay(state->mCaretFrame, nullptr);
   }
+
+  nsPresContext* pc = aReferenceFrame->PresContext();
+  pc->GetDocShell()->GetWindowDraggingAllowed(&mWindowDraggingAllowed);
 }
 
 void
@@ -1010,8 +1014,14 @@ nsDisplayListBuilder::LeavePresShell(nsIFrame* aReferenceFrame)
   NS_ASSERTION(CurrentPresShellState()->mPresShell ==
       aReferenceFrame->PresContext()->PresShell(),
       "Presshell mismatch");
+
   ResetMarkedFramesForDisplayList();
   mPresShellStates.SetLength(mPresShellStates.Length() - 1);
+
+  if (!mPresShellStates.IsEmpty()) {
+    nsPresContext* pc = CurrentPresContext();
+    pc->GetDocShell()->GetWindowDraggingAllowed(&mWindowDraggingAllowed);
+  }
 }
 
 void
@@ -1233,7 +1243,7 @@ nsDisplayListBuilder::RecomputeCurrentAnimatedGeometryRoot()
 void
 nsDisplayListBuilder::AdjustWindowDraggingRegion(nsIFrame* aFrame)
 {
-  if (!IsForPainting() || IsInSubdocument()) {
+  if (!mWindowDraggingAllowed || !IsForPainting()) {
     return;
   }
 

layout/base/nsDisplayList.h

@@ -907,6 +907,7 @@ private:
   // display list has a display port. An async-scrollable scroll frame is one
   // which WantsAsyncScroll().
   bool                           mHaveScrollableDisplayPort;
+  bool                           mWindowDraggingAllowed;
 };
 
 class nsDisplayItem;

layout/generic/nsFrame.cpp

@@ -2061,6 +2061,7 @@ nsIFrame::BuildDisplayListForStackingContext(nsDisplayListBuilder* aBuilder,
       aBuilder->SetLayerEventRegions(eventRegions);
       set.BorderBackground()->AppendNewToTop(eventRegions);
     }
+    aBuilder->AdjustWindowDraggingRegion(this);
     BuildDisplayList(aBuilder, dirtyRect, set);
   }
 
@@ -2456,6 +2457,7 @@ nsIFrame::BuildDisplayListForChild(nsDisplayListBuilder*   aBuilder,
       if (eventRegions) {
         eventRegions->AddFrame(aBuilder, child);
       }
+      aBuilder->AdjustWindowDraggingRegion(child);
       child->BuildDisplayList(aBuilder, dirty, aLists);
       aBuilder->DisplayCaret(child, dirty, aLists.Content());
 #ifdef DEBUG
@@ -2475,6 +2477,7 @@ nsIFrame::BuildDisplayListForChild(nsDisplayListBuilder*   aBuilder,
       aBuilder->SetLayerEventRegions(eventRegions);
       pseudoStack.BorderBackground()->AppendNewToTop(eventRegions);
     }
+    aBuilder->AdjustWindowDraggingRegion(child);
     child->BuildDisplayList(aBuilder, dirty, pseudoStack);
     aBuilder->DisplayCaret(child, dirty, pseudoStack.Content());
 

layout/xul/nsBoxFrame.cpp

@@ -1332,8 +1332,6 @@ nsBoxFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
       aBuilder->AddWindowExcludeGlassRegion(
           nsRect(aBuilder->ToReferenceFrame(this), GetSize()));
     }
-
-    aBuilder->AdjustWindowDraggingRegion(this);
   }
 
   nsDisplayListCollection tempLists;