Bug 800166 - Fire a low-memory notification when a B2G process is backgrounded. r=gwagner,bent

dom/ipc/ProcessPriorityManager.cpp

@@ -298,6 +298,13 @@ ProcessPriorityManager::OnGracePeriodTimerFired()
 
   mGracePeriodTimer = nullptr;
   hal::SetProcessPriority(getpid(), PROCESS_PRIORITY_BACKGROUND);
+
+  // We're in the background; dump as much memory as we can.
+  nsCOMPtr<nsIMemoryReporterManager> mgr =
+    do_GetService("@mozilla.org/memory-reporter-manager;1");
+  if (mgr) {
+    mgr->MinimizeMemoryUsage(/* callback = */ nullptr);
+  }
 }
 
 } // anonymous namespace

xpcom/base/nsIMemoryReporter.idl

@@ -295,7 +295,8 @@ interface nsIMemoryReporterManager : nsISupports
 
   /*
    * Run a series of GC/CC's in an attempt to minimize the application's memory
-   * usage.  When we're finished, we invoke the given runnable.
+   * usage.  When we're finished, we invoke the given runnable if it's not
+   * null.
    */
   void minimizeMemoryUsage(in nsIRunnable callback);
 };