scrollbars=no ignored for window.open() calls. Implement a stack-based helper class that will push a null JSContext to make our calls into Gecko privileged. sr=smfr, b=324907

camino/src/browser/nsAlertController.mm

@@ -35,9 +35,8 @@
  *
  * ***** END LICENSE BLOCK ***** */
 
-struct JSContext; // allow nsIJSContextStack to be included without sucking in JS headers
-#include "nsIJSContextStack.h"
 #include "nsServiceManagerUtils.h"
+#include "GeckoUtils.h"
 
 #import "nsAlertController.h"
 #import "CHBrowserService.h"
@@ -133,9 +132,9 @@ const int kLabelCheckboxAdjustment = 2; // # pixels the label must be pushed dow
   }
 
   int result = NSAlertErrorReturn;
-
-  nsCOMPtr<nsIJSContextStack> stack(do_GetService("@mozilla.org/js/xpc/ContextStack;1"));
-  if (stack && NS_SUCCEEDED(stack->Push(nsnull)))
+  nsresult rv = NS_OK;
+  StNullJSContextScope hack(&rv);
+  if (NS_SUCCEEDED(rv))
   {
     // be paranoid; we don't want to throw Obj-C exceptions over C++ code
     NS_DURING
@@ -146,10 +145,6 @@ const int kLabelCheckboxAdjustment = 2; // # pixels the label must be pushed dow
     NS_HANDLER
       NSLog(@"Exception caught in safeRunModalForWindow:relativeToWindow: %@", localException);
     NS_ENDHANDLER
-
-    JSContext* cx;
-    stack->Pop(&cx);
-    NS_ASSERTION(cx == nsnull, "JSContextStack mismatch");
   }
     
   return result;

camino/src/embedding/CHBrowserService.mm

@@ -55,6 +55,7 @@
 #include "nsIMIMEInfo.h"
 #include "nsIPref.h"
 #include "nsIObserverService.h"
+#include "GeckoUtils.h"
 
 NSString* const InitEmbeddingNotificationName = @"InitEmebedding";    // this is actually broadcast from MainController
 NSString* const TermEmbeddingNotificationName = @"TermEmbedding";
@@ -224,7 +225,16 @@ CHBrowserService::CreateChromeWindow(nsIWebBrowserChrome *parent,
 #endif
     return NS_ERROR_FAILURE;
   }
-    
+  
+  // Push a null JSContext on the JS stack, before we create the chrome window.
+  // Otherwise, a webpage invoking some JS to do window.open() will be last on the JS stack.
+  // And once we start fixing up our newly created chrome window (to hide the scrollbar,
+  // for example) Gecko will think it's the *webpage*, and webpages are not allowed
+  // to do that.  see bug 324907.
+  nsresult rv = NS_OK;
+  StNullJSContextScope hack(&rv);
+  NS_ENSURE_SUCCESS(rv, rv);
+  
   nsCOMPtr<nsIWindowCreator> browserChrome(do_QueryInterface(parent));
   return browserChrome->CreateChromeWindow(parent, chromeFlags, _retval);
 }

camino/src/extensions/GeckoUtils.h

@@ -38,7 +38,10 @@
 #ifndef __GeckoUtils_h__
 #define __GeckoUtils_h__
 
+#include "nsServiceManagerUtils.h"
 #include "nsString.h"
+#include "jsapi.h"
+#include "nsIJSContextStack.h"
 
 class nsIDOMNode;
 class nsIDOMElement;
@@ -46,6 +49,7 @@ class nsIDocShell;
 class nsIURI;
 class nsIEditor;
 
+
 class GeckoUtils
 {
   public:
@@ -66,5 +70,32 @@ class GeckoUtils
     static void FindDocShellForURI(nsIURI *aURI, nsIDocShell *aRoot, nsIDocShell **outMatch);
 };
 
+/* Stack-based utility that will push a null JSContext onto the JS stack during the
+   length of its lifetime.
 
+   For example, this is needed when some unprivileged JS code executes from a webpage. 
+   If we try to call into Gecko then, the current JSContext will be the webpage, and so 
+   Gecko might deny *us* the right to do something. For this reason we push a null JSContext, 
+   to make sure that whatever we want to do will be allowed. 
+*/
+class StNullJSContextScope {
+public:
+  StNullJSContextScope(nsresult *rv) {
+    mStack = do_GetService("@mozilla.org/js/xpc/ContextStack;1", rv);
+    if (NS_SUCCEEDED(*rv) && mStack)
+      *rv = mStack->Push(nsnull);
+  }
+  
+  ~StNullJSContextScope() {
+    if (mStack) {
+      JSContext *ctx;
+      mStack->Pop(&ctx);
+      NS_ASSERTION(!ctx, "Popped JSContext not null!");
+    }
+  }
+  
+private:
+  nsCOMPtr<nsIJSContextStack> mStack;
+};
+    
 #endif