Bug 836654 - Part 5: Add nsIMozBrowserFrame::isExpectingSystemMessage. r=bz

content/base/src/nsGkAtomList.h

@@ -342,6 +342,7 @@ GK_ATOM(events, "events")
 GK_ATOM(excludeResultPrefixes, "exclude-result-prefixes")
 GK_ATOM(excludes, "excludes")
 GK_ATOM(expr, "expr")
+GK_ATOM(expectingSystemMessage, "expecting-system-message")
 GK_ATOM(extends, "extends")
 GK_ATOM(extensionElementPrefixes, "extension-element-prefixes")
 GK_ATOM(face, "face")

content/html/content/src/nsGenericHTMLFrameElement.cpp

@@ -321,6 +321,19 @@ nsGenericHTMLFrameElement::GetReallyIsApp(bool *aOut)
   return NS_OK;
 }
 
+/* [infallible] */ NS_IMETHODIMP
+nsGenericHTMLFrameElement::GetIsExpectingSystemMessage(bool *aOut)
+{
+  *aOut = false;
+
+  if (!nsIMozBrowserFrame::GetReallyIsApp()) {
+    return NS_OK;
+  }
+
+  *aOut = HasAttr(kNameSpaceID_None, nsGkAtoms::expectingSystemMessage);
+  return NS_OK;
+}
+
 NS_IMETHODIMP
 nsGenericHTMLFrameElement::GetAppManifestURL(nsAString& aOut)
 {

dom/interfaces/html/nsIMozBrowserFrame.idl

@@ -30,6 +30,16 @@ interface nsIMozBrowserFrame : nsIDOMMozBrowserFrame
    */
   [infallible] readonly attribute boolean reallyIsApp;
 
+  /**
+   * This corresponds to the expecting-system-message attribute, which tells us
+   * whether we should expect that this frame will receive a system message once
+   * it starts up.
+   *
+   * It's the embedder's job to set this attribute on a frame.  Its presence
+   * might cause us to increase the priority of the frame's process.
+   */
+  [infallible] readonly attribute boolean isExpectingSystemMessage;
+
   /**
    * Gets this frame's app manifest URL, if the frame really is an app frame.
    * Otherwise, returns the empty string.