From a73ca835ccff1f310d0f9ba2eb3566dac0e9f288 Mon Sep 17 00:00:00 2001
From: Mats Palmgren <matspal@gmail.com>
Date: Mon, 30 Dec 2013 11:17:33 +0000
Subject: [PATCH] Bug 946929 - Part 2, adding more temporary diagnostic code. 
 r=roc

---
 layout/base/nsPresContext.cpp | 40 ++++++++++++++++++++++++++++++++---
 1 file changed, 37 insertions(+), 3 deletions(-)

diff --git a/layout/base/nsPresContext.cpp b/layout/base/nsPresContext.cpp
index e42ff99641fb..3d747ccbef87 100644
--- a/layout/base/nsPresContext.cpp
+++ b/layout/base/nsPresContext.cpp
@@ -70,6 +70,19 @@ using namespace mozilla;
 using namespace mozilla::dom;
 using namespace mozilla::layers;
 
+// BEGIN temporary diagnostic stuff for bug 946929
+struct PCLink;
+static PCLink* sTopPCLink;
+struct PCLink {
+  PCLink(const char* w, nsPresContext* aPC)
+    : prev(sTopPCLink), pc(aPC), where(w) { sTopPCLink = this; }
+  ~PCLink() { sTopPCLink = prev; }
+  PCLink* prev;
+  nsPresContext* pc;
+  const char* where;
+};
+// END temporary diagnostic stuff for bug 946929
+
 uint8_t gNotifySubDocInvalidationData;
 
 /**
@@ -125,7 +138,7 @@ nsPresContext::MakeColorPref(const nsString& aColor)
 
 static void DumpPresContextState(nsPresContext* aPC)
 {
-  printf_stderr("PresContext(%p) ", aPC);
+  printf_stderr("PresContext(%p) %s", aPC, aPC->IsRoot()?"ROOT ":"");
   nsIURI* uri = aPC->Document()->GetDocumentURI();
   if (uri) {
     nsAutoCString uriSpec;
@@ -136,7 +149,7 @@ static void DumpPresContextState(nsPresContext* aPC)
   }
   nsIPresShell* shell = aPC->GetPresShell();
   if (shell) {
-    printf_stderr("PresShell(%p) - IsDestroying(%i) IsFrozen(%i) IsActive(%i) IsVisible(%i) IsNeverPainting(%i) GetRootFrame(%p)",
+    printf_stderr("PresShell - IsDestroying(%i) IsFrozen(%i) IsActive(%i) IsVisible(%i) IsNeverPainting(%i) GetRootFrame(%p)",
                   shell->IsDestroying(),
                   shell->IsFrozen(),
                   shell->IsActive(),
@@ -156,11 +169,27 @@ nsPresContext::IsDOMPaintEventPending()
   if (!GetDisplayRootPresContext() ||
       !GetDisplayRootPresContext()->GetRootPresContext()) {
     printf_stderr("Failed to find root pres context, dumping pres context and ancestors\n");
+    for (PCLink* p = sTopPCLink; p; p = p->prev) {
+      printf_stderr("%s %p ", p->where, p->pc);
+    }
+    if (sTopPCLink) printf_stderr("\n");
     nsPresContext* pc = this;
     for (;;) {
       DumpPresContextState(pc);
       nsPresContext* parent = pc->GetParentPresContext();
-      if (!parent)
+      if (!parent) {
+        nsIDocument* doc = pc->Document();
+        if (doc) {
+          doc = doc->GetParentDocument();
+          if (doc) {
+            nsIPresShell* shell = doc->GetShell();
+            if (shell) {
+              parent = shell->GetPresContext();
+            }
+          }
+        }
+      }
+      if (!parent || parent == pc)
         break;
       pc = parent;
     }
@@ -281,6 +310,9 @@ nsPresContext::nsPresContext(nsIDocument* aDocument, nsPresContextType aType)
 
 nsPresContext::~nsPresContext()
 {
+  if (sTopPCLink) {
+    printf_stderr("~nsPresContext %p %p\n", this, mShell);
+  }
   NS_PRECONDITION(!mShell, "Presshell forgot to clear our mShell pointer");
   SetShell(nullptr);
 
@@ -2404,6 +2436,7 @@ NotifyDidPaintSubdocumentCallback(nsIDocument* aDocument, void* aData)
   if (shell) {
     nsPresContext* pc = shell->GetPresContext();
     if (pc) {
+      PCLink pcl("NotifyDidPaintSubdocumentCallback", pc);
       pc->NotifyDidPaintForSubtree(closure->mFlags);
       if (pc->IsDOMPaintEventPending()) {
         closure->mNeedsAnotherDidPaintNotification = true;
@@ -2986,6 +3019,7 @@ NotifyDidPaintForSubtreeCallback(nsITimer *aTimer, void *aClosure)
   nsAutoScriptBlocker blockScripts;
   // This is a fallback if we don't get paint events for some reason
   // so we'll just pretend both layer painting and compositing happened.
+  PCLink pcl("NotifyDidPaintForSubtreeCallback", presContext);
   presContext->NotifyDidPaintForSubtree(
       nsIPresShell::PAINT_LAYERS | nsIPresShell::PAINT_COMPOSITE);
 }