From b77a18712626bded9e12fb0c26881641965a4cf3 Mon Sep 17 00:00:00 2001
From: Nicolas Silva <nsilva@mozilla.com>
Date: Mon, 28 Dec 2015 10:46:25 +0100
Subject: [PATCH] Bug 1176024 - Have TextureClient::Lock check that it can
 expose a DrawTarget when it makes sense. r=Bas

---
 gfx/layers/client/TextureClient.cpp | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/gfx/layers/client/TextureClient.cpp b/gfx/layers/client/TextureClient.cpp
index 3e2646111d6..13778783481 100644
--- a/gfx/layers/client/TextureClient.cpp
+++ b/gfx/layers/client/TextureClient.cpp
@@ -363,6 +363,15 @@ TextureClient::Lock(OpenMode aMode)
   mIsLocked = mData->Lock(aMode, mReleaseFenceHandle.IsValid() ? &mReleaseFenceHandle : nullptr);
   mOpenMode = aMode;
 
+  if (mIsLocked && CanExposeDrawTarget() && (aMode & OpenMode::OPEN_WRITE) && NS_IsMainThread()) {
+    if (!BorrowDrawTarget()) {
+      // Failed to get a DrawTarget, means we won't be able to write into the
+      // texture, might as well fail now.
+      Unlock();
+      return false;
+    }
+  }
+
   return mIsLocked;
 }