Add "sample locations" feature to GrProcessor

src/gpu/gl/GrGLGpu.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 GrGLGpu_DEFINED
 #define GrGLGpu_DEFINED
 
@@ skipping 200 matching lines @@
 
     void onResolveRenderTarget(GrRenderTarget* target) override;
 
     void onDraw(const DrawArgs&, const GrNonInstancedVertices&) override;
 
     bool onCopySurface(GrSurface* dst,
                        GrSurface* src,
                        const SkIRect& srcRect,
                        const SkIPoint& dstPoint) override;
 
+    void onGetMultisampleSpecs(GrRenderTarget*,
+                               const GrStencilSettings&,
+                               int* effectiveSampleCnt,
+                               SamplePattern*) override;
+
     // binds texture unit in GL
     void setTextureUnit(int unitIdx);
 
     // Flushes state from GrPipeline to GL. Returns false if the state couldn't be set.
     bool flushGLState(const DrawArgs&);
 
     // Sets up vertex attribute pointers and strides. On return indexOffsetInBytes gives the offset
     // an into the index buffer. It does not account for vertices.startIndex() but rather the start
     // index is relative to the returned offset.
     void setupGeometry(const GrPrimitiveProcessor&,
@@ skipping 373 matching lines @@
     } fPLSSetupProgram;
 
     bool fHWPLSEnabled;
     bool fPLSHasBeenUsed;
 
     typedef GrGpu INHERITED;
     friend class GrGLPathRendering; // For accessing setTextureUnit.
 };
 
 #endif