Bug 1259246. Move nsIPresShell::GetRealPrimaryFrameFor to nsLayoutUtils::GetRealPrimaryFrameFor. r=dholbert

The function doesn't need to be a non-static member of nsIPresShell: it only checks if the document of the passed in element matches the presshell's document, and then the remaining code could be static. It has only one user, nsDocumentViewer::FindContainerView, and it doesn't care about the specific presshell, it just wants the primary frame, so it doesn't need the document check.

This lets us simplify nsDocumentViewer::FindContainerView because it had to jump through hoops to get the presshell.

layout/base/nsDocumentViewer.cpp

@@ -2462,24 +2462,7 @@ nsDocumentViewer::FindContainerView()
         return nullptr;
       }
 
-      nsCOMPtr<nsIPresShell> parentPresShell;
+      nsIFrame* subdocFrame = nsLayoutUtils::GetRealPrimaryFrameFor(containerElement);
-      nsCOMPtr<nsIDocument> parentDoc = containerElement->GetUncomposedDoc();
-      if (parentDoc) {
-        parentPresShell = parentDoc->GetShell();
-      }
-
-      if (!parentPresShell) {
-        nsCOMPtr<nsIDocShellTreeItem> parentDocShellItem;
-        docShell->GetParent(getter_AddRefs(parentDocShellItem));
-        if (parentDocShellItem) {
-          nsCOMPtr<nsIDocShell> parentDocShell = do_QueryInterface(parentDocShellItem);
-          parentPresShell = parentDocShell->GetPresShell();
-        }
-      }
-      if (!parentPresShell) {
-        NS_WARNING("Subdocument container has no presshell");
-      } else {
-        nsIFrame* subdocFrame = parentPresShell->GetRealPrimaryFrameFor(containerElement);
       if (subdocFrame) {
         // subdocFrame might not be a subdocument frame; the frame
         // constructor can treat a <frame> as an inline in some XBL
@@ -2500,7 +2483,6 @@ nsDocumentViewer::FindContainerView()
       }
     }
   }
-  }
 
   return containerView;
 }

layout/base/nsIPresShell.h

@@ -497,15 +497,6 @@ public:
   */
   virtual nsCanvasFrame* GetCanvasFrame() const = 0;
 
-  /**
-   * Gets the real primary frame associated with the content object.
-   *
-   * In the case of absolutely positioned elements and floated elements,
-   * the real primary frame is the frame that is out of the flow and not the
-   * placeholder frame.
-   */
-  virtual nsIFrame* GetRealPrimaryFrameFor(nsIContent* aContent) const = 0;
-
   /**
    * Gets the placeholder frame associated with the specified frame. This is
    * a helper frame that forwards the request to the frame manager.

layout/base/nsLayoutUtils.cpp

@@ -1577,6 +1577,17 @@ nsLayoutUtils::GetStyleFrame(const nsIContent* aContent)
   return nsLayoutUtils::GetStyleFrame(frame);
 }
 
+/* static */ nsIFrame*
+nsLayoutUtils::GetRealPrimaryFrameFor(const nsIContent* aContent)
+{
+  nsIFrame *frame = aContent->GetPrimaryFrame();
+  if (!frame) {
+    return nullptr;
+  }
+
+  return nsPlaceholderFrame::GetRealFrameFor(frame);
+}
+
 nsIFrame*
 nsLayoutUtils::GetFloatFromPlaceholder(nsIFrame* aFrame) {
   NS_ASSERTION(nsGkAtoms::placeholderFrame == aFrame->GetType(),

layout/base/nsLayoutUtils.h

@@ -363,6 +363,15 @@ public:
    */
   static nsIFrame* GetStyleFrame(const nsIContent* aContent);
 
+  /**
+   * Gets the real primary frame associated with the content object.
+   *
+   * In the case of absolutely positioned elements and floated elements,
+   * the real primary frame is the frame that is out of the flow and not the
+   * placeholder frame.
+   */
+  static nsIFrame* GetRealPrimaryFrameFor(const nsIContent* aContent);
+
   /**
    * IsGeneratedContentFor returns true if aFrame is the outermost
    * frame for generated content of type aPseudoElement for aContent.

layout/base/nsPresShell.cpp

@@ -4552,18 +4552,6 @@ PresShell::StyleRuleRemoved(StyleSheetHandle aStyleSheet)
   RecordStyleSheetChange(aStyleSheet);
 }
 
-nsIFrame*
-PresShell::GetRealPrimaryFrameFor(nsIContent* aContent) const
-{
-  if (aContent->GetComposedDoc() != GetDocument()) {
-    return nullptr;
-  }
-  nsIFrame *primaryFrame = aContent->GetPrimaryFrame();
-  if (!primaryFrame)
-    return nullptr;
-  return nsPlaceholderFrame::GetRealFrameFor(primaryFrame);
-}
-
 nsIFrame*
 PresShell::GetPlaceholderFrameFor(nsIFrame* aFrame) const
 {

layout/base/nsPresShell.h

@@ -123,7 +123,6 @@ public:
   virtual nsresult ResizeReflowIgnoreOverride(nscoord aWidth, nscoord aHeight) override;
   virtual nsIPageSequenceFrame* GetPageSequenceFrame() const override;
   virtual nsCanvasFrame* GetCanvasFrame() const override;
-  virtual nsIFrame* GetRealPrimaryFrameFor(nsIContent* aContent) const override;
 
   virtual nsIFrame* GetPlaceholderFrameFor(nsIFrame* aFrame) const override;
   virtual void FrameNeedsReflow(nsIFrame *aFrame, IntrinsicDirty aIntrinsicDirty,