Bug 1156008 - Convert CapturingContentInfo::mContent to StaticRefPtr; r=roc

layout/base/nsIPresShell.h

@@ -22,6 +22,7 @@
 
 #include "mozilla/EventForwards.h"
 #include "mozilla/MemoryReporting.h"
+#include "mozilla/StaticPtr.h"
 #include "mozilla/WeakPtr.h"
 #include "gfxPoint.h"
 #include "nsTHashtable.h"
@@ -136,7 +137,7 @@ typedef struct CapturingContentInfo {
   bool mPointerLock;
   bool mRetargetToElement;
   bool mPreventDrag;
-  nsIContent* mContent;
+  mozilla::StaticRefPtr<nsIContent> mContent;
 } CapturingContentInfo;
 
 // d910f009-d209-74c1-6b04-30c83c051c78

layout/base/nsPresShell.cpp

@@ -199,7 +199,7 @@ using namespace mozilla::layout;
 
 CapturingContentInfo nsIPresShell::gCaptureInfo =
   { false /* mAllowed */, false /* mPointerLock */, false /* mRetargetToElement */,
-    false /* mPreventDrag */, nullptr /* mContent */ };
+    false /* mPreventDrag */ };
 nsIContent* nsIPresShell::gKeyDownTarget;
 nsClassHashtable<nsUint32HashKey, nsIPresShell::PointerCaptureInfo>* nsIPresShell::gPointerCaptureList;
 nsClassHashtable<nsUint32HashKey, nsIPresShell::PointerInfo>* nsIPresShell::gActivePointersIds;
@@ -3875,7 +3875,7 @@ PresShell::ClearMouseCaptureOnView(nsView* aView)
         if (view) {
           do {
             if (view == aView) {
-              NS_RELEASE(gCaptureInfo.mContent);
+              gCaptureInfo.mContent = nullptr;
               // the view containing the captured content likely disappeared so
               // disable capture for now.
               gCaptureInfo.mAllowed = false;
@@ -3890,7 +3890,7 @@ PresShell::ClearMouseCaptureOnView(nsView* aView)
       }
     }
 
-    NS_RELEASE(gCaptureInfo.mContent);
+    gCaptureInfo.mContent = nullptr;
   }
 
   // disable mouse capture until the next mousedown as a dialog has opened
@@ -3909,20 +3909,20 @@ nsIPresShell::ClearMouseCapture(nsIFrame* aFrame)
 
   // null frame argument means clear the capture
   if (!aFrame) {
-    NS_RELEASE(gCaptureInfo.mContent);
+    gCaptureInfo.mContent = nullptr;
     gCaptureInfo.mAllowed = false;
     return;
   }
 
   nsIFrame* capturingFrame = gCaptureInfo.mContent->GetPrimaryFrame();
   if (!capturingFrame) {
-    NS_RELEASE(gCaptureInfo.mContent);
+    gCaptureInfo.mContent = nullptr;
     gCaptureInfo.mAllowed = false;
     return;
   }
 
   if (nsLayoutUtils::IsAncestorFrameCrossDoc(aFrame, capturingFrame)) {
-    NS_RELEASE(gCaptureInfo.mContent);
+    gCaptureInfo.mContent = nullptr;
     gCaptureInfo.mAllowed = false;
   }
 }
@@ -6357,14 +6357,14 @@ nsIPresShell::SetCapturingContent(nsIContent* aContent, uint8_t aFlags)
     return;
   }
 
-  NS_IF_RELEASE(gCaptureInfo.mContent);
+  gCaptureInfo.mContent = nullptr;
 
   // only set capturing content if allowed or the CAPTURE_IGNOREALLOWED or
   // CAPTURE_POINTERLOCK flags are used.
   if ((aFlags & CAPTURE_IGNOREALLOWED) || gCaptureInfo.mAllowed ||
       (aFlags & CAPTURE_POINTERLOCK)) {
     if (aContent) {
-      NS_ADDREF(gCaptureInfo.mContent = aContent);
+      gCaptureInfo.mContent = aContent;
     }
     // CAPTURE_POINTERLOCK is the same as CAPTURE_RETARGETTOELEMENT & CAPTURE_IGNOREALLOWED
     gCaptureInfo.mRetargetToElement = ((aFlags & CAPTURE_RETARGETTOELEMENT) != 0) ||