Bug 1440815 - Add check to TextureClient::EnableReadLock() r=nical

gfx/layers/client/TextureClient.cpp

@@ -592,7 +592,12 @@ void
 TextureClient::EnableReadLock()
 {
   if (!mReadLock) {
-    mReadLock = NonBlockingTextureReadLock::Create(mAllocator);
+    if (mAllocator->GetTileLockAllocator()) {
+      mReadLock = NonBlockingTextureReadLock::Create(mAllocator);
+    } else {
+      // IPC is down
+      gfxCriticalError() << "TextureClient::EnableReadLock IPC is down";
+    }
   }
 }
 
@@ -1679,6 +1684,7 @@ ShmemTextureReadLock::ShmemTextureReadLock(LayersIPCChannel* aAllocator)
 {
   MOZ_COUNT_CTOR(ShmemTextureReadLock);
   MOZ_ASSERT(mClientAllocator);
+  MOZ_ASSERT(mClientAllocator->GetTileLockAllocator());
 #define MOZ_ALIGN_WORD(x) (((x) + 3) & ~3)
   if (mClientAllocator->GetTileLockAllocator()->AllocShmemSection(
       MOZ_ALIGN_WORD(sizeof(ShmReadLockInfo)), &mShmemSection)) {