[GPU] Add explicit byte order and PM vs. UPM 8888 configs

Review URL: http://codereview.appspot.com/5347042/



git-svn-id: http://skia.googlecode.com/svn/trunk@2618 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/gpu/GrGpu.cpp b/src/gpu/GrGpu.cpp
index b7d1395..7da560e 100644
--- a/src/gpu/GrGpu.cpp
+++ b/src/gpu/GrGpu.cpp
@@ -242,11 +242,12 @@
 bool GrGpu::readPixels(GrRenderTarget* target,
                        int left, int top, int width, int height,
                        GrPixelConfig config, void* buffer,
-                       size_t rowBytes) {
-
+                       size_t rowBytes, bool invertY) {
+    GrAssert(GrPixelConfigIsUnpremultiplied(config) ==
+             GrPixelConfigIsUnpremultiplied(target->config()));
     this->handleDirtyContext();
     return this->onReadPixels(target, left, top, width, height,
-                              config, buffer, rowBytes);
+                              config, buffer, rowBytes, invertY);
 }
 
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