Give GrDrawTarget a back ptr to its owning GrContext.
Review URL: https://codereview.appspot.com/7395055

git-svn-id: http://skia.googlecode.com/svn/trunk@7850 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/gpu/GrGpu.cpp b/src/gpu/GrGpu.cpp
index c9aa046..b5cdc5c 100644
--- a/src/gpu/GrGpu.cpp
+++ b/src/gpu/GrGpu.cpp
@@ -26,8 +26,8 @@
 #define DEBUG_INVAL_BUFFER    0xdeadcafe
 #define DEBUG_INVAL_START_IDX -1
 
-GrGpu::GrGpu()
-    : fContext(NULL)
+GrGpu::GrGpu(GrContext* context)
+    : GrDrawTarget(context)
     , fResetTimestamp(kExpiredTimestamp+1)
     , fVertexPool(NULL)
     , fIndexPool(NULL)