From 335b4750cb5b84cb6a4d72c935a3b4180c5f502a Mon Sep 17 00:00:00 2001
From: Daniel Holbert <dholbert@cs.stanford.edu>
Date: Thu, 20 Aug 2020 06:16:04 +0000
Subject: [PATCH] Bug 1660166 part 3: Remove a redundant member-variable that
 represents the total number of pages. r=hiro

Before this patch stack, nsPageSequenceFrame and every nsPageFrame each
individually tracked the number of pages.

As of the previous patch, we've coalesced the nsPageFrame variables into a
single variable that lives on nsSharedPageData.  This patch here replaces
nsPageSequenceFrame's member-var with that nsSharedPageData variable, too.

Depends on D87696

Differential Revision: https://phabricator.services.mozilla.com/D87697
---
 layout/generic/nsPageSequenceFrame.cpp | 5 +----
 layout/generic/nsPageSequenceFrame.h   | 6 +++---
 2 files changed, 4 insertions(+), 7 deletions(-)

diff --git a/layout/generic/nsPageSequenceFrame.cpp b/layout/generic/nsPageSequenceFrame.cpp
index 5a9c83af5235..bdf716bc541b 100644
--- a/layout/generic/nsPageSequenceFrame.cpp
+++ b/layout/generic/nsPageSequenceFrame.cpp
@@ -52,7 +52,6 @@ nsPageSequenceFrame::nsPageSequenceFrame(ComputedStyle* aStyle,
     : nsContainerFrame(aStyle, aPresContext, kClassID),
       mMaxSheetSize(mWritingMode),
       mScrollportSize(mWritingMode),
-      mTotalPages(-1),
       mCalledBeginPage(false),
       mCurrentCanvasListSetup(false) {
   mPageData = MakeUnique<nsSharedPageData>();
@@ -406,10 +405,8 @@ nsresult nsPageSequenceFrame::StartPrint(nsPresContext* aPresContext,
 
   // If printing a range of pages make sure at least the starting page
   // number is valid
-  mTotalPages = mFrames.GetLength();
-
   if (mDoingPageRange) {
-    if (mFromPageNum > mTotalPages) {
+    if (mFromPageNum > mPageData->mTotNumPages) {
       return NS_ERROR_INVALID_ARG;
     }
   }
diff --git a/layout/generic/nsPageSequenceFrame.h b/layout/generic/nsPageSequenceFrame.h
index 302d8ea6a8e4..a3a22292a70c 100644
--- a/layout/generic/nsPageSequenceFrame.h
+++ b/layout/generic/nsPageSequenceFrame.h
@@ -39,7 +39,8 @@ class nsSharedPageData {
   nsString mDocURL;
   nsFont mHeadFootFont;
 
-  // Total number of pages:
+  // Total number of pages (populated by PrintedSheetFrame when it determines
+  // that it's reflowed the final page):
   int32_t mTotNumPages = 0;
 
   // Margin for headers and footers; it defaults to 4/100 of an inch on UNIX
@@ -90,7 +91,7 @@ class nsPageSequenceFrame final : public nsContainerFrame {
   nsresult PrintNextPage();
   void ResetPrintCanvasList();
   int32_t GetCurrentPageNum() const { return mPageNum; }
-  int32_t GetNumPages() const { return mTotalPages; }
+  int32_t GetNumPages() const { return mPageData->mTotNumPages; }
   bool IsDoingPrintRange() const { return mDoingPageRange; }
   void GetPrintRange(int32_t* aFromPage, int32_t* aToPage) const;
   nsresult DoPageEnd();
@@ -154,7 +155,6 @@ class nsPageSequenceFrame final : public nsContainerFrame {
 
   // Async Printing
   int32_t mPageNum;
-  int32_t mTotalPages;
   int32_t mFromPageNum;
   int32_t mToPageNum;