Bug 1030090 - tests shouldn't destroy gfxPrefs, r=bjacob

gfx/tests/gtest/TestAsyncPanZoomController.cpp

@@ -36,9 +36,6 @@ protected:
     gfxPrefs::GetSingleton();
     AsyncPanZoomController::SetThreadAssertionsEnabled(false);
   }
-  virtual void TearDown() {
-    gfxPrefs::DestroySingleton();
-  }
 };
 
 class APZCTreeManagerTester : public ::testing::Test {
@@ -47,9 +44,6 @@ protected:
     gfxPrefs::GetSingleton();
     AsyncPanZoomController::SetThreadAssertionsEnabled(false);
   }
-  virtual void TearDown() {
-    gfxPrefs::DestroySingleton();
-  }
 };
 
 class MockContentController : public GeckoContentController {

gfx/tests/gtest/TestGfxPrefs.cpp

@@ -16,15 +16,11 @@
 // result through this API.
 
 TEST(GfxPrefs, Singleton) {
-  ASSERT_FALSE(gfxPrefs::SingletonExists());
   gfxPrefs::GetSingleton();
   ASSERT_TRUE(gfxPrefs::SingletonExists());
-  gfxPrefs::DestroySingleton();
-  ASSERT_FALSE(gfxPrefs::SingletonExists());
 }
 
 TEST(GfxPrefs, LiveValues) {
-  ASSERT_FALSE(gfxPrefs::SingletonExists());
   gfxPrefs::GetSingleton();
   ASSERT_TRUE(gfxPrefs::SingletonExists());
 
@@ -36,13 +32,9 @@ TEST(GfxPrefs, LiveValues) {
 
   // Live uint32_t, default 2
   ASSERT_TRUE(gfxPrefs::MSAALevel() == 2);
-
-  gfxPrefs::DestroySingleton();
-  ASSERT_FALSE(gfxPrefs::SingletonExists());
 }
 
 TEST(GfxPrefs, OnceValues) {
-  ASSERT_FALSE(gfxPrefs::SingletonExists());
   gfxPrefs::GetSingleton();
   ASSERT_TRUE(gfxPrefs::SingletonExists());
 
@@ -60,8 +52,5 @@ TEST(GfxPrefs, OnceValues) {
 
   // Once float, default -1 (should be OK with ==)
   ASSERT_TRUE(gfxPrefs::APZMaxVelocity() == -1.0f);
-
-  gfxPrefs::DestroySingleton();
-  ASSERT_FALSE(gfxPrefs::SingletonExists());
 }
 

gfx/thebes/gfxPrefs.cpp

@@ -11,6 +11,7 @@
 using namespace mozilla;
 
 gfxPrefs* gfxPrefs::sInstance = nullptr;
+bool gfxPrefs::sInstanceHasBeenDestroyed = false;
 
 void
 gfxPrefs::DestroySingleton()
@@ -18,7 +19,9 @@ gfxPrefs::DestroySingleton()
   if (sInstance) {
     delete sInstance;
     sInstance = nullptr;
+    sInstanceHasBeenDestroyed = true;
   }
+  MOZ_ASSERT(!SingletonExists());
 }
 
 bool

gfx/thebes/gfxPrefs.h

@@ -234,9 +234,11 @@ public:
   // Manage the singleton:
   static gfxPrefs& GetSingleton()
   {
+    MOZ_ASSERT(!sInstanceHasBeenDestroyed, "Should never recreate a gfxPrefs instance!");
     if (!sInstance) {
       sInstance = new gfxPrefs;
     }
+    MOZ_ASSERT(SingletonExists());
     return *sInstance;
   }
   static void DestroySingleton();
@@ -244,6 +246,7 @@ public:
 
 private:
   static gfxPrefs* sInstance;
+  static bool sInstanceHasBeenDestroyed;
 
 private:
   // Creating these to avoid having to include Preferences.h in the .h