GPU: add failure checks for the scratch textures used in Gaussian blur.

https://codereview.appspot.com/6744047/

On behalf of senorblanco



git-svn-id: http://skia.googlecode.com/svn/trunk@6014 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/gpu/GrContext.cpp b/src/gpu/GrContext.cpp
index 63e5c2c..1ea2906 100644
--- a/src/gpu/GrContext.cpp
+++ b/src/gpu/GrContext.cpp
@@ -1804,6 +1804,9 @@
     GrAutoScratchTexture temp1, temp2;
     GrTexture* dstTexture = temp1.set(this, desc);
     GrTexture* tempTexture = canClobberSrc ? srcTexture : temp2.set(this, desc);
+    if (NULL == dstTexture || NULL == tempTexture) {
+        return NULL;
+    }
 
     GrPaint paint;
     paint.reset();