Support GL_RGB textures and render targets.

Bug= skia:7533

Change-Id: Iba30e90dbf2574368b773bb5cf2ebd5219559717
Reviewed-on: https://skia-review.googlesource.com/108188
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
diff --git a/dm/DMSrcSink.cpp b/dm/DMSrcSink.cpp
index 09c88af..cd4f111 100644
--- a/dm/DMSrcSink.cpp
+++ b/dm/DMSrcSink.cpp
@@ -1881,7 +1881,8 @@
         canvas->getGrContext()->contextPriv().dumpGpuStats(log);
 #endif
     }
-    if (info.colorType() == kRGB_565_SkColorType || info.colorType() == kARGB_4444_SkColorType) {
+    if (info.colorType() == kRGB_565_SkColorType || info.colorType() == kARGB_4444_SkColorType ||
+        info.colorType() == kRGB_888x_SkColorType) {
         // We don't currently support readbacks into these formats on the GPU backend. Convert to
         // 32 bit.
         info = SkImageInfo::Make(size.width(), size.height(), kRGBA_8888_SkColorType,