Fix NULL access

src/gpu/SkGr.cpp

 /*
  * Copyright 2010 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkGr.h"
 
 #include "GrCaps.h"
@@ skipping 98 matching lines @@
         stretch->fHeight = GrNextPow2(height);
     } else if (width < ctx->caps()->minTextureSize() ||
                height < ctx->caps()->minTextureSize()) {
         // The small texture issues appear to be with tiling. Hence it seems ok to scale them
         // up using the GPU. If issues persist we may need to CPU-stretch.
         doStretch = true;
         stretch->fWidth = SkTMax(width, ctx->caps()->minTextureSize());
         stretch->fHeight = SkTMax(height, ctx->caps()->minTextureSize());
     }
     if (doStretch) {
-        switch(params->filterMode()) {
-            case GrTextureParams::kNone_FilterMode:
-                stretch->fType = Stretch::kNearest_Type;
-                break;
-            case GrTextureParams::kBilerp_FilterMode:
-            case GrTextureParams::kMipMap_FilterMode:
-                stretch->fType = Stretch::kBilerp_Type;
-                break;
+        if (params) {
+            switch(params->filterMode()) {
+                case GrTextureParams::kNone_FilterMode:
+                    stretch->fType = Stretch::kNearest_Type;
+                    break;
+                case GrTextureParams::kBilerp_FilterMode:
+                case GrTextureParams::kMipMap_FilterMode:
+                    stretch->fType = Stretch::kBilerp_Type;
+                    break;
+            }
+        } else {
+            stretch->fType = Stretch::kBilerp_Type;
         }
     } else {
         stretch->fWidth  = -1;
         stretch->fHeight = -1;
         stretch->fType = Stretch::kNone_Type;
     }
 }
 
 static bool make_stretched_key(const GrUniqueKey& origKey, const Stretch& stretch,
                                GrUniqueKey* stretchedKey) {
@@ skipping 657 matching lines @@
     }
     return SkImageInfo::Make(w, h, ct, at);
 }
 
 
 void GrWrapTextureInBitmap(GrTexture* src, int w, int h, bool isOpaque, SkBitmap* dst) {
     const SkImageInfo info = GrMakeInfoFromTexture(src, w, h, isOpaque);
     dst->setInfo(info);
     dst->setPixelRef(SkNEW_ARGS(SkGrPixelRef, (info, src)))->unref();
 }