Bug 1234049 - Ensure we always invalidate new PresShells that are created for an inactive DocShell upon reactivating them. r=smaug

layout/base/nsPresShell.cpp

@@ -745,6 +745,7 @@ PresShell::PresShell()
   mSelectionFlags = nsISelectionDisplay::DISPLAY_TEXT | nsISelectionDisplay::DISPLAY_IMAGES;
   mIsThemeSupportDisabled = false;
   mIsActive = true;
+  mIsHidden = false;
   // FIXME/bug 735029: find a better solution to this problem
 #if defined(MOZ_WIDGET_ANDROID) && !defined(MOZ_ANDROID_APZ)
   // The java pan/zoom code uses this to mean approximately "request a
@@ -10403,6 +10404,10 @@ void PresShell::QueryIsActive()
   if (docshell) {
     bool isActive;
     nsresult rv = docshell->GetIsActive(&isActive);
+    // Even though in theory the docshell here could be "Inactive and
+    // Foreground", thus implying aIsHidden=false for SetIsActive(),
+    // this is a newly created PresShell so we'd like to invalidate anyway
+    // upon being made active to ensure that the contents get painted.
     if (NS_SUCCEEDED(rv))
       SetIsActive(isActive);
   }
@@ -10440,6 +10445,11 @@ PresShell::SetIsActive(bool aIsActive, bool aIsHidden)
   NS_PRECONDITION(mDocument, "should only be called with a document");
 
   mIsActive = aIsActive;
+
+  // Keep track of whether we've called TabChild::MakeHidden() or not.
+  // This can still be true even if aIsHidden is false.
+  mIsHidden |= aIsHidden;
+
   nsPresContext* presContext = GetPresContext();
   if (presContext &&
       presContext->RefreshDriver()->PresContext() == presContext) {
@@ -10479,10 +10489,14 @@ PresShell::SetIsActive(bool aIsActive, bool aIsHidden)
   // and (ii) has easy access to the TabChild.  So we use this
   // notification to signal the TabChild to drop its layer tree and
   // stop trying to repaint.
-  if (aIsHidden) {
+  if (mIsHidden) {
     if (TabChild* tab = TabChild::GetFrom(this)) {
       if (aIsActive) {
         tab->MakeVisible();
+        // The only time we should set this to false is when
+        // TabChild::MakeVisible() is called.
+        mIsHidden = false;
+
         if (!mIsZombie) {
           if (nsIFrame* root = mFrameConstructor->GetRootFrame()) {
             FrameLayerBuilder::InvalidateAllLayersForFrame(

layout/base/nsPresShell.h

@@ -494,6 +494,8 @@ protected:
   friend class nsPresShellEventCB;
 
   bool mCaretEnabled;
+
+  bool mIsHidden;
 #ifdef DEBUG
   nsStyleSet* CloneStyleSet(nsStyleSet* aSet);
   bool VerifyIncrementalReflow();