Check for xfer barriers in GrBatch, auto-issue barriers in GrGpu

src/gpu/batches/GrBatch.h

Index: src/gpu/batches/GrBatch.h
diff --git a/src/gpu/batches/GrBatch.h b/src/gpu/batches/GrBatch.h
index 815369124a3e71a47a109e8c5a5404782575d42e..35844cd99a533d6e6a4e5ab56dd93ac0948d23f0 100644
--- a/src/gpu/batches/GrBatch.h
+++ b/src/gpu/batches/GrBatch.h
@@ -54,16 +54,14 @@ public:
     virtual void getInvariantOutputColor(GrInitInvariantOutput* out) const = 0;
     virtual void getInvariantOutputCoverage(GrInitInvariantOutput* out) const = 0;
 
-    bool combineIfPossible(GrBatch* that) {
+    bool combineIfPossible(GrBatch* that, const GrCaps& caps) {
         if (this->classID() != that->classID()) {
             return false;
         }
 
-        return this->onCombineIfPossible(that);
+        return this->onCombineIfPossible(that, caps);
     }
 
-    virtual bool onCombineIfPossible(GrBatch*) = 0;
-
     virtual void generateGeometry(GrBatchTarget*) = 0;
 
     const SkRect& bounds() const { return fBounds; }
@@ -162,6 +160,8 @@ protected:
     SkRect fBounds;
 
 private:
+    virtual bool onCombineIfPossible(GrBatch*, const GrCaps& caps) = 0;
+
     /*
      * initBatchTracker is a hook for the some additional overrides / optimization possibilities
      * from the GrXferProcessor.