From 37ebeead76333cd45227a43f4491be228f606409 Mon Sep 17 00:00:00 2001
From: Justin Lebar <justin.lebar@gmail.com>
Date: Thu, 25 Apr 2013 20:53:26 -0400
Subject: [PATCH] Bug 860799 - Part 1: Give frames expecting a system message
 priority at least BACKGROUND_PERCEIVABLE, so long as either haven't yet
 handled the system message or are holding the CPU/high-priority wake lock.
 r=khuey

---
 dom/ipc/ProcessPriorityManager.cpp | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/dom/ipc/ProcessPriorityManager.cpp b/dom/ipc/ProcessPriorityManager.cpp
index c6974fb9954..f0d465c96ce 100644
--- a/dom/ipc/ProcessPriorityManager.cpp
+++ b/dom/ipc/ProcessPriorityManager.cpp
@@ -28,6 +28,7 @@
 #include "nsIDOMDocument.h"
 #include "nsPIDOMWindow.h"
 #include "StaticPtr.h"
+#include "nsIMozBrowserFrame.h"
 #include "nsIObserver.h"
 #include "nsITimer.h"
 #include "nsPrintfCString.h"
@@ -228,6 +229,7 @@ public:
   const nsAutoCString& NameWithComma();
 
   bool HasAppType(const char* aAppType);
+  bool IsExpectingSystemMessage();
 
   void OnAudioChannelProcessChanged(nsISupports* aSubject);
   void OnRemoteBrowserFrameShown(nsISupports* aSubject);
@@ -702,6 +704,27 @@ ParticularProcessPriorityManager::HasAppType(const char* aAppType)
   return false;
 }
 
+bool
+ParticularProcessPriorityManager::IsExpectingSystemMessage()
+{
+  const InfallibleTArray<PBrowserParent*>& browsers =
+    mContentParent->ManagedPBrowserParent();
+  for (uint32_t i = 0; i < browsers.Length(); i++) {
+    TabParent* tp = static_cast<TabParent*>(browsers[i]);
+    nsCOMPtr<nsIDOMElement> ownerElement = tp->GetOwnerElement();
+    nsCOMPtr<nsIMozBrowserFrame> bf = do_QueryInterface(ownerElement);
+    if (!bf) {
+      continue;
+    }
+
+    if (bf->GetIsExpectingSystemMessage()) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
 ProcessPriority
 ParticularProcessPriorityManager::ComputePriority()
 {
@@ -724,6 +747,11 @@ ParticularProcessPriorityManager::ComputePriority()
     return PROCESS_PRIORITY_FOREGROUND;
   }
 
+  if ((mHoldsCPUWakeLock || mHoldsHighPriorityWakeLock) &&
+      IsExpectingSystemMessage()) {
+    return PROCESS_PRIORITY_BACKGROUND_PERCEIVABLE;
+  }
+
   AudioChannelService* service = AudioChannelService::GetAudioChannelService();
   if (service->ProcessContentOrNormalChannelIsActive(ChildID())) {
     return PROCESS_PRIORITY_BACKGROUND_PERCEIVABLE;