Make ANGLE perf decisions be runtime rather than compile time

src/gpu/gl/GrGLCaps.h

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #ifndef GrGLCaps_DEFINED
 #define GrGLCaps_DEFINED
@@ skipping 263 matching lines @@
      * we found LATC under. The default is LATC.
      */
     enum LATCAlias {
         kLATC_LATCAlias,
         kRGTC_LATCAlias,
         k3DC_LATCAlias
     };
 
     LATCAlias latcAlias() const { return fLATCAlias; }
 
+    bool rgba8888PixelsOpsAreSlow() const { return fRGBA8888PixelsOpsAreSlow; }
+    bool partialFBOReadIsSlow() const { return fPartialFBOReadIsSlow; }
+
     GrGLSLCaps* glslCaps() const { return reinterpret_cast<GrGLSLCaps*>(fShaderCaps.get()); }
 
 private:
     void init(const GrContextOptions&, const GrGLContextInfo&, const GrGLInterface*);
     bool hasPathRenderingSupport(const GrGLContextInfo&, const GrGLInterface*);
 
     /**
      * Maintains a bit per GrPixelConfig. It is used to avoid redundantly
      * performing glCheckFrameBufferStatus for the same config.
      */
@@ skipping 79 matching lines @@
     bool fInstancedDrawingSupport : 1;
     bool fDirectStateAccessSupport : 1;
     bool fDebugSupport : 1;
     bool fES2CompatibilitySupport : 1;
     bool fMultisampleDisableSupport : 1;
     bool fUseNonVBOVertexAndIndexDynamicData : 1;
     bool fIsCoreProfile : 1;
     bool fFullClearIsFree : 1;
     bool fBindFragDataLocationSupport : 1;
     bool fSRGBWriteControl : 1;
+    bool fRGBA8888PixelsOpsAreSlow : 1;
+    bool fPartialFBOReadIsSlow : 1;
 
     struct ReadPixelsSupportedFormat {
         GrGLenum fFormat;
         GrGLenum fType;
         GrGLenum fFboFormat;
 
         bool operator==(const ReadPixelsSupportedFormat& rhs) const {
             return fFormat    == rhs.fFormat
                 && fType      == rhs.fType
                 && fFboFormat == rhs.fFboFormat;
         }
     };
     mutable SkTHashMap<ReadPixelsSupportedFormat, bool> fReadPixelsSupportedCache;
 
     typedef GrCaps INHERITED;
 };
 
 #endif