small fix for cache clear

BUG=skia:

Review URL: https://codereview.chromium.org/695873002

src/gpu/GrClipMaskManager.h

@@ -80,12 +80,6 @@ public:
         return kAlpha_ClipMaskType == fCurrClipMaskType;
     }
 
-    void invalidateStencilMask() {
-        if (kStencil_ClipMaskType == fCurrClipMaskType) {
-            fCurrClipMaskType = kNone_ClipMaskType;
-        }
-    }
-
     GrContext* getContext() {
         return fAACache.getContext();
     }

src/gpu/GrDrawTarget.h

@@ -968,6 +968,16 @@ public:
      */
     virtual void clearStencilClip(const SkIRect& rect, bool insideClip, GrRenderTarget* = NULL) = 0;
 
+    /**
+     * Release any resources that are cached but not currently in use. This
+     * is intended to give an application some recourse when resources are low.
+     */
+    virtual void purgeResources() SK_OVERRIDE {
+        // The clip mask manager can rebuild all its clip masks so just
+        // get rid of them all.
+        fClipMaskManager.purgeResources();
+    };
+
 protected:
     GrClipMaskManager           fClipMaskManager;
 

src/gpu/GrGpu.h

@@ -275,12 +275,6 @@ public:
                                   bool insideClip,
                                   GrRenderTarget* renderTarget = NULL) SK_OVERRIDE;
 
-    virtual void purgeResources() SK_OVERRIDE {
-        // The clip mask manager can rebuild all its clip masks so just
-        // get rid of them all.
-        fClipMaskManager.purgeResources();
-    }
-
     // After the client interacts directly with the 3D context state the GrGpu
     // must resync its internal state and assumptions about 3D context state.
     // Each time this occurs the GrGpu bumps a timestamp.
@@ -471,10 +465,6 @@ private:
     void prepareIndexPool();
 
     void resetContext() {
-        // We call this because the client may have messed with the
-        // stencil buffer. Perhaps we should detect whether it is a
-        // internally created stencil buffer and if so skip the invalidate.
-        fClipMaskManager.invalidateStencilMask();
         this->onResetContext(fResetBits);
         fResetBits = 0;
         ++fResetTimestamp;