Attempt to somewhat simplify GrContext::readSurfacePixels interaction with GrGpu.

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 39 matching lines @@
     GrGLPathRendering* glPathRendering() {
         SkASSERT(glCaps().shaderCaps()->pathRenderingSupport());
         return static_cast<GrGLPathRendering*>(pathRendering());
     }
 
     void discard(GrRenderTarget*) override;
 
     // Used by GrGLProgram to configure OpenGL state.
     void bindTexture(int unitIdx, const GrTextureParams& params, GrGLTexture* texture);
 
+    bool getReadPixelsInfo(GrSurface* srcSurface, int readWidth, int readHeight, size_t rowBytes,
+                           GrPixelConfig readConfig, DrawPreference*,
+                           ReadPixelTempDrawInfo*) override;
+
+
     // GrGpu overrides
-    GrPixelConfig preferredReadPixelsConfig(GrPixelConfig readConfig,
-                                            GrPixelConfig surfaceConfig) const override;
     GrPixelConfig preferredWritePixelsConfig(GrPixelConfig writeConfig,
                                              GrPixelConfig surfaceConfig) const override;
     bool canWriteTexturePixels(const GrTexture*, GrPixelConfig srcConfig) const override;
-    bool readPixelsWillPayForYFlip(GrRenderTarget* renderTarget,
-                                   int left, int top,
-                                   int width, int height,
-                                   GrPixelConfig config,
-                                   size_t rowBytes) const override;
-    bool fullReadPixelsIsFasterThanPartial() const override;
 
     bool initCopySurfaceDstDesc(const GrSurface* src, GrSurfaceDesc* desc) const override;
 
     // These functions should be used to bind GL objects. They track the GL state and skip redundant
     // bindings. Making the equivalent glBind calls directly will confuse the state tracking.
     void bindVertexArray(GrGLuint id) {
         fHWGeometryState.setVertexArrayID(this, id);
     }
     void bindIndexBufferAndDefaultVertexArray(GrGLuint id) {
         fHWGeometryState.setIndexBufferIDOnDefaultVertexArray(this, id);
@@ skipping 418 matching lines @@
 
     // we record what stencil format worked last time to hopefully exit early
     // from our loop that tries stencil formats and calls check fb status.
     int fLastSuccessfulStencilFmtIdx;
 
     typedef GrGpu INHERITED;
     friend class GrGLPathRendering; // For accessing setTextureUnit.
 };
 
 #endif