Bug 1308459 - Rename RefreshDriver::PresContext() to hint about its behavior, r=tnikkel

--HG--
extra : rebase_source : 50cf1fd7f1ee052e182ae3fa84ce8648e46143cd

layout/base/nsPresContext.cpp

@@ -987,7 +987,7 @@ nsPresContext::DetachShell()
     mRestyleManager->Disconnect();
     mRestyleManager = nullptr;
   }
-  if (mRefreshDriver && mRefreshDriver->PresContext() == this) {
+  if (mRefreshDriver && mRefreshDriver->GetPresContext() == this) {
     mRefreshDriver->Disconnect();
     // Can't null out the refresh driver here.
   }

layout/base/nsPresContext.h

@@ -134,7 +134,8 @@ class nsRootPresContext;
 // An interface for presentation contexts. Presentation contexts are
 // objects that provide an outer context for a presentation shell.
 
-class nsPresContext : public nsIObserver {
+class nsPresContext : public nsIObserver,
+                      public mozilla::SupportsWeakPtr<nsPresContext> {
 public:
   typedef mozilla::FramePropertyTable FramePropertyTable;
   typedef mozilla::LangGroupFontPrefs LangGroupFontPrefs;
@@ -145,6 +146,7 @@ public:
   NS_DECL_NSIOBSERVER
   NS_DECL_AND_IMPL_ZEROING_OPERATOR_NEW
   NS_DECL_CYCLE_COLLECTION_CLASS(nsPresContext)
+  MOZ_DECLARE_WEAKREFERENCE_TYPENAME(nsPresContext)
 
   enum nsPresContextType {
     eContext_Galley,       // unpaginated screen presentation

layout/base/nsPresShell.cpp

@@ -1295,7 +1295,7 @@ PresShell::Destroy()
     mHiddenInvalidationObserverRefreshDriver->RemovePresShellToInvalidateIfHidden(this);
   }
 
-  if (rd->PresContext() == GetPresContext()) {
+  if (rd->GetPresContext() == GetPresContext()) {
     rd->RevokeViewManagerFlush();
   }
 
@@ -8997,7 +8997,7 @@ PresShell::Freeze()
 
   nsPresContext* presContext = GetPresContext();
   if (presContext &&
-      presContext->RefreshDriver()->PresContext() == presContext) {
+      presContext->RefreshDriver()->GetPresContext() == presContext) {
     presContext->RefreshDriver()->Freeze();
   }
 
@@ -9055,7 +9055,7 @@ PresShell::Thaw()
 {
   nsPresContext* presContext = GetPresContext();
   if (presContext &&
-      presContext->RefreshDriver()->PresContext() == presContext) {
+      presContext->RefreshDriver()->GetPresContext() == presContext) {
     presContext->RefreshDriver()->Thaw();
   }
 
@@ -10911,7 +10911,7 @@ PresShell::SetIsActive(bool aIsActive)
 
   nsPresContext* presContext = GetPresContext();
   if (presContext &&
-      presContext->RefreshDriver()->PresContext() == presContext) {
+      presContext->RefreshDriver()->GetPresContext() == presContext) {
     presContext->RefreshDriver()->SetThrottled(!mIsActive);
   }
 
@@ -11142,7 +11142,7 @@ nsIPresShell::FontSizeInflationEnabled()
 void
 PresShell::PausePainting()
 {
-  if (GetPresContext()->RefreshDriver()->PresContext() != GetPresContext())
+  if (GetPresContext()->RefreshDriver()->GetPresContext() != GetPresContext())
     return;
 
   mPaintingIsFrozen = true;
@@ -11152,7 +11152,7 @@ PresShell::PausePainting()
 void
 PresShell::ResumePainting()
 {
-  if (GetPresContext()->RefreshDriver()->PresContext() != GetPresContext())
+  if (GetPresContext()->RefreshDriver()->GetPresContext() != GetPresContext())
     return;
 
   mPaintingIsFrozen = false;

layout/base/nsRefreshDriver.cpp

@@ -173,7 +173,8 @@ public:
       NS_ASSERTION(mRootRefreshDrivers.Contains(aDriver), "RemoveRefreshDriver for a refresh driver that's not in the root refresh list!");
       mRootRefreshDrivers.RemoveElement(aDriver);
     } else {
-      nsPresContext* rootContext = aDriver->PresContext()->GetRootPresContext();
+      nsPresContext* pc = aDriver->GetPresContext();
+      nsPresContext* rootContext = pc ? pc->GetRootPresContext() : nullptr;
       // During PresContext shutdown, we can't accurately detect
       // if a root refresh driver exists or not. Therefore, we have to
       // search and find out which list this driver exists in.
@@ -227,7 +228,8 @@ protected:
 
   bool IsRootRefreshDriver(nsRefreshDriver* aDriver)
   {
-    nsPresContext* rootContext = aDriver->PresContext()->GetRootPresContext();
+    nsPresContext* pc = aDriver->GetPresContext();
+    nsPresContext* rootContext = pc ? pc->GetRootPresContext() : nullptr;
     if (!rootContext) {
       return false;
     }
@@ -2100,7 +2102,8 @@ nsRefreshDriver::IsWaitingForPaint(mozilla::TimeStamp aTime)
 
   // Try find the 'root' refresh driver for the current window and check
   // if that is waiting for a paint.
-  nsPresContext *rootContext = PresContext()->GetRootPresContext();
+  nsPresContext* pc = GetPresContext();
+  nsPresContext* rootContext = pc ? pc->GetRootPresContext() : nullptr;
   if (rootContext) {
     nsRefreshDriver *rootRefresh = rootContext->RefreshDriver();
     if (rootRefresh && rootRefresh != this) {

layout/base/nsRefreshDriver.h

@@ -14,7 +14,7 @@
 
 #include "mozilla/TimeStamp.h"
 #include "mozilla/Vector.h"
-
+#include "mozilla/WeakPtr.h"
 #include "mozFlushType.h"
 #include "nsTObserverArray.h"
 #include "nsTArray.h"
@@ -273,7 +273,7 @@ public:
   /**
    * Return the prescontext we were initialized with
    */
-  nsPresContext* PresContext() const { return mPresContext; }
+  nsPresContext* GetPresContext() const { return mPresContext; }
 
   /**
    * PBackgroundChild actor is created asynchronously in content process.
@@ -381,8 +381,8 @@ private:
   ProfilerBacktrace* mReflowCause;
   ProfilerBacktrace* mStyleCause;
 
-  nsPresContext *mPresContext; // weak; pres context passed in constructor
-                               // and unset in Disconnect
+  // nsPresContext passed in constructor and unset in Disconnect.
+  mozilla::WeakPtr<nsPresContext> mPresContext;
 
   RefPtr<nsRefreshDriver> mRootRefresh;