Reland of Add guards to GrTextureProvider

include/gpu/GrTextureProvider.h

Index: include/gpu/GrTextureProvider.h
diff --git a/include/gpu/GrTextureProvider.h b/include/gpu/GrTextureProvider.h
index 5635583d80fef393a746ae75f32edc0d2a3c8025..46f381da81f1fd5b5c0cdd82ba13829d95f58c52 100644
--- a/include/gpu/GrTextureProvider.h
+++ b/include/gpu/GrTextureProvider.h
@@ -10,6 +10,8 @@
 
 #include "GrTexture.h"
 #include "SkImageFilter.h"
+
+class GrSingleOwner;
 
 class SK_API GrTextureProvider {
 public:
@@ -42,15 +44,7 @@
     }
 
     /** Finds a texture by unique key. If the texture is found it is ref'ed and returned. */
-    GrTexture* findAndRefTextureByUniqueKey(const GrUniqueKey& key) {
-        GrGpuResource* resource = this->findAndRefResourceByUniqueKey(key);
-        if (resource) {
-            GrTexture* texture = static_cast<GrSurface*>(resource)->asTexture();
-            SkASSERT(texture);
-            return texture;
-        }
-        return NULL;
-    }
+    GrTexture* findAndRefTextureByUniqueKey(const GrUniqueKey& key);
 
     /**
      * Determines whether a texture is associated with the unique key. If the texture is found it
@@ -134,7 +128,7 @@
      GrRenderTarget* wrapBackendRenderTarget(const GrBackendRenderTargetDesc& desc);
 
 protected:
-    GrTextureProvider(GrGpu* gpu, GrResourceCache* cache) : fCache(cache), fGpu(gpu) {}
+    GrTextureProvider(GrGpu* gpu, GrResourceCache* cache, GrSingleOwner* singleOwner);
 
     /**
      * Assigns a unique key to a resource. If the key is associated with another resource that
@@ -186,6 +180,9 @@
 private:
     GrResourceCache* fCache;
     GrGpu* fGpu;
+
+    // In debug builds we guard against improper thread handling
+    SkDEBUGCODE(mutable GrSingleOwner* fSingleOwner;)
 };
 
 #endif