Bug 84106. Actually pass a cache key to web browser persist so that POST result pages have a chance of being read from cache. Also change nsWebBrowserPersist to accept a session history entry, not just an nsIWebPageDescriptor or necko cache key, as its cache key argument. r=gavin, r+sr=jst

embedding/components/webbrowserpersist/public/nsIWebBrowserPersist.idl

@@ -148,7 +148,9 @@ interface nsIWebBrowserPersist : nsICancelable
    *                   may also support <CODE>nsnull</CODE> to imply the currently
    *                   loaded URI.
    * @param aCacheKey  An object representing the URI in the cache or
-   *                   <CODE>nsnull</CODE>.
+   *                   <CODE>nsnull</CODE>.  This can be a necko cache key,
+   *                   an nsIWebPageDescriptor, or the currentDescriptor of an
+   *                   nsIWebPageDescriptor.
    * @param aReferrer  The referrer URI to pass with an HTTP request or
    *                   <CODE>nsnull</CODE>.
    * @param aPostData  Post data to pass with an HTTP request or

embedding/components/webbrowserpersist/src/nsWebBrowserPersist.cpp

@@ -1218,22 +1218,24 @@ nsresult nsWebBrowserPersist::SaveURIInternal(
     if (aCacheKey)
     {
         // Test if the cache key is actually a web page descriptor (docshell)
-        nsCOMPtr<nsIWebPageDescriptor> webPageDescriptor = do_QueryInterface(aCacheKey);
+        // or session history entry.
+        nsCOMPtr<nsISHEntry> shEntry = do_QueryInterface(aCacheKey);
+        if (!shEntry)
+        {
+            nsCOMPtr<nsIWebPageDescriptor> webPageDescriptor =
+                do_QueryInterface(aCacheKey);
             if (webPageDescriptor)
             {
                 nsCOMPtr<nsISupports> currentDescriptor;
                 webPageDescriptor->GetCurrentDescriptor(getter_AddRefs(currentDescriptor));
-            if (currentDescriptor)
-            {
-                // Descriptor is actually a session history entry
-                nsCOMPtr<nsISHEntry> shEntry = do_QueryInterface(currentDescriptor);
-                NS_ASSERTION(shEntry, "The descriptor is meant to be a session history entry");
+                shEntry = do_QueryInterface(currentDescriptor);
+            }
+        }
+
         if (shEntry)
         {
             shEntry->GetCacheKey(getter_AddRefs(cacheKey));
         }
-            }
-        }
         else
         {
             // Assume a plain cache key

toolkit/content/contentAreaUtils.js

@@ -108,7 +108,7 @@ function saveURL(aURL, aFileName, aFilePickerTitleKey, aShouldBypassCache,
                  aSkipPrompt, aReferrer)
 {
   internalSave(aURL, null, aFileName, null, null, aShouldBypassCache,
-               aFilePickerTitleKey, null, aReferrer, aSkipPrompt);
+               aFilePickerTitleKey, null, aReferrer, aSkipPrompt, null);
 }
 
 // Just like saveURL, but will get some info off the image before
@@ -139,7 +139,8 @@ function saveImageURL(aURL, aFileName, aFilePickerTitleKey, aShouldBypassCache,
     }
   }
   internalSave(aURL, null, aFileName, contentDisposition, contentType,
-               aShouldBypassCache, aFilePickerTitleKey, null, aReferrer, aSkipPrompt);
+               aShouldBypassCache, aFilePickerTitleKey, null, aReferrer,
+               aSkipPrompt, null);
 }
 
 function saveFrameDocument()
@@ -155,20 +156,32 @@ function saveDocument(aDocument, aSkipPrompt)
     throw "Must have a document when calling saveDocument";
 
   // We want to use cached data because the document is currently visible.
+  var ifreq =
+    aDocument.defaultView
+             .QueryInterface(Components.interfaces.nsIInterfaceRequestor);
+
   var contentDisposition = null;
   try {
     contentDisposition =
-      aDocument.defaultView
-               .QueryInterface(Components.interfaces.nsIInterfaceRequestor)
-               .getInterface(Components.interfaces.nsIDOMWindowUtils)
-               .getDocumentMetadata("content-disposition");
+      ifreq.getInterface(Components.interfaces.nsIDOMWindowUtils)
+           getDocumentMetadata("content-disposition");
   } catch (ex) {
     // Failure to get a content-disposition is ok
   }
+
+  var cacheKey = null;
+  try {
+    cacheKey =
+      ifreq.getInterface(Components.interfaces.nsIWebNavigation)
+           .QueryInterface(Components.interfaces.nsIWebPageDescriptor);
+  } catch (ex) {
+    // We might not find it in the cache.  Oh, well.
+  }
+
   internalSave(aDocument.location.href, aDocument, null, contentDisposition,
                aDocument.contentType, false, null, null,
                aDocument.referrer ? makeURI(aDocument.referrer) : null,
-               aSkipPrompt);
+               aSkipPrompt, cacheKey);
 }
 
 function DownloadListener(win, transfer) {
@@ -252,14 +265,20 @@ const kSaveAsType_Text     = 2; // Save document, converting to plain text.
  * @param aSkipPrompt [optional]
  *        If set to true, we will attempt to save the file to the
  *        default downloads folder without prompting.
+ * @param aCacheKey [optional]
+ *        If set will be passed to saveURI.  See nsIWebBrowserPersist for
+ *        allowed values.
  */
 function internalSave(aURL, aDocument, aDefaultFileName, aContentDisposition,
                       aContentType, aShouldBypassCache, aFilePickerTitleKey,
-                      aChosenData, aReferrer, aSkipPrompt)
+                      aChosenData, aReferrer, aSkipPrompt, aCacheKey)
 {
   if (aSkipPrompt == undefined)
     aSkipPrompt = false;
 
+  if (aCacheKey == undefined)
+    aCacheKey = null;
+
   // Note: aDocument == null when this code is used by save-link-as...
   var saveMode = GetSaveModeForContentType(aContentType);
   var isDocument = aDocument != null && saveMode != SAVEMODE_FILEONLY;
@@ -376,7 +395,7 @@ function internalSave(aURL, aDocument, aDefaultFileName, aContentDisposition,
             persistArgs.target, "", null, null, null, persist);
     persist.progressListener = new DownloadListener(window, tr);
     persist.saveURI((aChosenData ? aChosenData.uri : source),
-                    null, aReferrer, persistArgs.postData, null,
+                    aCacheKey, aReferrer, persistArgs.postData, null,
                     persistArgs.target);
   }
 }