Add flag bits for partial GrContext reset

src/gpu/GrGpu.cpp

Index: src/gpu/GrGpu.cpp
diff --git a/src/gpu/GrGpu.cpp b/src/gpu/GrGpu.cpp
index ae98b54bea8dd054f2657b94d8fc75c17ab9ab1f..5d6c62fc931ffbde8a212e83b993ccd4fa585a32 100644
--- a/src/gpu/GrGpu.cpp
+++ b/src/gpu/GrGpu.cpp
@@ -30,12 +30,12 @@ static const int INDEX_POOL_IB_COUNT = 4;
 GrGpu::GrGpu(GrContext* context)
     : GrDrawTarget(context)
     , fResetTimestamp(kExpiredTimestamp+1)
+    , fResetBits(kAll_GrBackendState)
     , fVertexPool(NULL)
     , fIndexPool(NULL)
     , fVertexPoolUseCnt(0)
     , fIndexPoolUseCnt(0)
-    , fQuadIndexBuffer(NULL)
-    , fContextIsDirty(true) {
+    , fQuadIndexBuffer(NULL) {
 
     fClipMaskManager.setGpu(this);