Fix BGRA readback on Android

src/gpu/gl/GrGpuGL.cpp

Index: src/gpu/gl/GrGpuGL.cpp
diff --git a/src/gpu/gl/GrGpuGL.cpp b/src/gpu/gl/GrGpuGL.cpp
index cc9994385a0273f6dd6cdfec8b33f06218c1b01e..5845d7a673ac36c3b267084740ba5505acf8f9e7 100644
--- a/src/gpu/gl/GrGpuGL.cpp
+++ b/src/gpu/gl/GrGpuGL.cpp
@@ -231,29 +231,32 @@ void GrGpuGL::fillInConfigRenderableTable() {
     }
 }
 
-namespace {
-GrPixelConfig preferred_pixel_ops_config(GrPixelConfig cpuConfig, GrPixelConfig surfaceConfig) {
-    if (GR_GL_RGBA_8888_PIXEL_OPS_SLOW && kRGBA_8888_GrPixelConfig == cpuConfig) {
+GrPixelConfig GrGpuGL::preferredReadPixelsConfig(GrPixelConfig readConfig,
+                                                 GrPixelConfig surfaceConfig) const {
+    if (GR_GL_RGBA_8888_PIXEL_OPS_SLOW && kRGBA_8888_GrPixelConfig == readConfig) {
         return kBGRA_8888_GrPixelConfig;
-    } else if (GrBytesPerPixel(cpuConfig) == 4 &&
-                GrPixelConfigSwapRAndB(cpuConfig) == surfaceConfig) {
+    } else if (fGLContext.info().isMesa() &&
+               GrBytesPerPixel(readConfig) == 4 &&
+               GrPixelConfigSwapRAndB(readConfig) == surfaceConfig) {
         // Mesa 3D takes a slow path on when reading back  BGRA from an RGBA surface and vice-versa.
         // Perhaps this should be guarded by some compiletime or runtime check.
         return surfaceConfig;
+    } else if (readConfig == kBGRA_8888_GrPixelConfig &&
+               !this->glCaps().readPixelsSupported(this->glInterface(),
+                                                   GR_GL_BGRA, GR_GL_UNSIGNED_BYTE)) {
+        return kRGBA_8888_GrPixelConfig;
     } else {
-        return cpuConfig;
+        return readConfig;
     }
 }
-}
-
-GrPixelConfig GrGpuGL::preferredReadPixelsConfig(GrPixelConfig readConfig,
-                                                 GrPixelConfig surfaceConfig) const {
-    return preferred_pixel_ops_config(readConfig, surfaceConfig);
-}
 
 GrPixelConfig GrGpuGL::preferredWritePixelsConfig(GrPixelConfig writeConfig,
                                                   GrPixelConfig surfaceConfig) const {
-    return preferred_pixel_ops_config(writeConfig, surfaceConfig);
+    if (GR_GL_RGBA_8888_PIXEL_OPS_SLOW && kRGBA_8888_GrPixelConfig == writeConfig) {
+        return kBGRA_8888_GrPixelConfig;
+    } else {
+        return writeConfig;
+    }
 }
 
 bool GrGpuGL::canWriteTexturePixels(const GrTexture* texture, GrPixelConfig srcConfig) const {