import changes from tenfourfox:

- #500: M1458270 M1452576 M1459162 M1450688 M1456975 M1459693 M1464784 (14a6deb01)

widget/GfxInfoBase.cpp

@@ -45,6 +45,7 @@ using mozilla::MutexAutoLock;
 
 nsTArray<GfxDriverInfo>* GfxInfoBase::mDriverInfo;
 bool GfxInfoBase::mDriverInfoObserverInitialized;
+bool GfxInfoBase::mShutdownOccurred;
 
 // Observes for shutdown so that the child GfxDriverInfo list is freed.
 class ShutdownObserver : public nsIObserver
@@ -64,11 +65,17 @@ public:
     delete GfxInfoBase::mDriverInfo;
     GfxInfoBase::mDriverInfo = nullptr;
 
-    for (uint32_t i = 0; i < DeviceFamilyMax; i++)
+    for (uint32_t i = 0; i < DeviceFamilyMax; i++) {
       delete GfxDriverInfo::mDeviceFamilies[i];
+      GfxDriverInfo::mDeviceFamilies[i] = nullptr;
+    }
 
-    for (uint32_t i = 0; i < DeviceVendorMax; i++)
+    for (uint32_t i = 0; i < DeviceVendorMax; i++) {
       delete GfxDriverInfo::mDeviceVendors[i];
+      GfxDriverInfo::mDeviceVendors[i] = nullptr;
+    }
+
+    GfxInfoBase::mShutdownOccurred = true;
 
     return NS_OK;
   }
@@ -911,6 +918,13 @@ GfxInfoBase::GetFeatureStatusImpl(int32_t aFeature,
     return NS_OK;
   }
 
+  if (mShutdownOccurred) {
+    // This is futile; we've already commenced shutdown and our blocklists have
+    // been deleted. We may want to look into resurrecting the blocklist instead
+    // but for now, just don't even go there.
+    return NS_OK;
+  }
+
   // If an operating system was provided by the derived GetFeatureStatusImpl,
   // grab it here. Otherwise, the OS is unknown.
   OperatingSystem os = DRIVER_OS_UNKNOWN;

widget/GfxInfoBase.h

@@ -72,6 +72,7 @@ public:
 
   static nsTArray<GfxDriverInfo>* mDriverInfo;
   static bool mDriverInfoObserverInitialized;
+  static bool mShutdownOccurred;
 
   virtual nsString Model() { return EmptyString(); }
   virtual nsString Hardware() { return EmptyString(); }

widget/cocoa/GfxInfo.mm

@@ -335,6 +335,10 @@ GfxInfo::GetFeatureStatusImpl(int32_t aFeature,
   if (aOS)
     *aOS = os;
 
+  if (mShutdownOccurred) {
+    return NS_OK;
+  }
+
   // Don't evaluate special cases when we're evaluating the downloaded blocklist.
   if (!aDriverInfo.Length()) {
     if (aFeature == nsIGfxInfo::FEATURE_WEBGL_MSAA) {