Add support for creating texture backed images where Skia will delete the texture.

Review URL: https://codereview.chromium.org/1187523005
diff --git a/src/gpu/GrGpu.cpp b/src/gpu/GrGpu.cpp
index a6e9654..d46d09d 100644
--- a/src/gpu/GrGpu.cpp
+++ b/src/gpu/GrGpu.cpp
@@ -175,9 +175,9 @@
     }
 }
 
-GrTexture* GrGpu::wrapBackendTexture(const GrBackendTextureDesc& desc) {
+GrTexture* GrGpu::wrapBackendTexture(const GrBackendTextureDesc& desc, GrWrapOwnership ownership) {
     this->handleDirtyContext();
-    GrTexture* tex = this->onWrapBackendTexture(desc);
+    GrTexture* tex = this->onWrapBackendTexture(desc, ownership);
     if (NULL == tex) {
         return NULL;
     }
@@ -191,9 +191,10 @@
     }
 }
 
-GrRenderTarget* GrGpu::wrapBackendRenderTarget(const GrBackendRenderTargetDesc& desc) {
+GrRenderTarget* GrGpu::wrapBackendRenderTarget(const GrBackendRenderTargetDesc& desc,
+                                               GrWrapOwnership ownership) {
     this->handleDirtyContext();
-    return this->onWrapBackendRenderTarget(desc);
+    return this->onWrapBackendRenderTarget(desc, ownership);
 }
 
 GrVertexBuffer* GrGpu::createVertexBuffer(size_t size, bool dynamic) {