Add GrGpu support for Vulkan command buffer flush

src/gpu/GrGpu.h

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrGpu_DEFINED
 #define GrGpu_DEFINED
 
@@ skipping 331 matching lines @@
             , fDesc(desc) {
             SkASSERT(primProc && pipeline && desc);
         }
         const GrPrimitiveProcessor* fPrimitiveProcessor;
         const GrPipeline* fPipeline;
         const GrProgramDesc* fDesc;
     };
 
     void draw(const DrawArgs&, const GrVertices&);
 
-    // Called by drawtarget when flushing. Provides a hook for working around an ARM PLS driver bug.
-    virtual void performFlushWorkaround();
+    // Called by drawtarget when flushing. 
+    // Provides a hook for post-flush actions (e.g. PLS reset and Vulkan command buffer submits).
+    virtual void finishDrawTarget() {}
 
     ///////////////////////////////////////////////////////////////////////////
     // Debugging and Stats
 
     class Stats {
     public:
 #if GR_GPU_STATS
         Stats() { this->reset(); }
 
         void reset() {
@@ skipping 210 matching lines @@
     ResetTimestamp                                                      fResetTimestamp;
     uint32_t                                                            fResetBits;
     // The context owns us, not vice-versa, so this ptr is not ref'ed by Gpu.
     GrContext*                                                          fContext;
 
     friend class GrPathRendering;
     typedef SkRefCnt INHERITED;
 };
 
 #endif