Restore read pixels perf on ANGLE

src/gpu/gl/GrGLGpu.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "GrGLGpu.h"
 #include "GrGLGLSL.h"
@@ skipping 1754 matching lines @@
                                      width >= this->caps()->minTextureSize() &&
                                      height >= this->caps()->minTextureSize();
 
     // Start off assuming that any temp draw should be to the readConfig, then check if that will
     // be inefficient.
     GrPixelConfig srcConfig = srcSurface->config();
     tempDrawInfo->fTempSurfaceDesc.fConfig = readConfig;
 
     if (GR_GL_RGBA_8888_PIXEL_OPS_SLOW && kRGBA_8888_GrPixelConfig == readConfig) {
         tempDrawInfo->fTempSurfaceDesc.fConfig = kBGRA_8888_GrPixelConfig;
+        tempDrawInfo->fSwapRAndB = true;
+        ElevateDrawPreference(drawPreference, kGpuPrefersDraw_DrawPreference);
     } else if (kMesa_GrGLDriver == this->glContext().driver() &&
                GrBytesPerPixel(readConfig) == 4 &&
                GrPixelConfigSwapRAndB(readConfig) == srcConfig) {
         // Mesa 3D takes a slow path on when reading back  BGRA from an RGBA surface and vice-versa.
         // Better to do a draw with a R/B swap and then read as the original config.
         tempDrawInfo->fTempSurfaceDesc.fConfig = srcConfig;
         tempDrawInfo->fSwapRAndB = true;
         ElevateDrawPreference(drawPreference, kGpuPrefersDraw_DrawPreference);
     } else if (readConfig == kBGRA_8888_GrPixelConfig &&
                !this->glCaps().readPixelsSupported(this->glInterface(), GR_GL_BGRA,
@@ skipping 1425 matching lines @@
             this->setVertexArrayID(gpu, 0);
         }
         int attrCount = gpu->glCaps().maxVertexAttributes();
         if (fDefaultVertexArrayAttribState.count() != attrCount) {
             fDefaultVertexArrayAttribState.resize(attrCount);
         }
         attribState = &fDefaultVertexArrayAttribState;
     }
     return attribState;
 }