Add GL_ANGLE_pack_reverse_row_order to command buffer

gpu/command_buffer/service/gles2_cmd_decoder.cc

Index: gpu/command_buffer/service/gles2_cmd_decoder.cc
===================================================================
--- gpu/command_buffer/service/gles2_cmd_decoder.cc	(revision 112221)
+++ gpu/command_buffer/service/gles2_cmd_decoder.cc	(working copy)
@@ -5801,15 +5801,24 @@
     SetGLError(GL_INVALID_ENUM, "glPixelStorei: pname GL_INVALID_ENUM");
     return error::kNoError;
   }
-  if (!validators_->pixel_store_alignment.IsValid(param)) {
-    SetGLError(GL_INVALID_VALUE, "glPixelSTore: param GL_INVALID_VALUE");
-    return error::kNoError;
+  switch (pname) {
+    case GL_PACK_ALIGNMENT:
+    case GL_UNPACK_ALIGNMENT:
+        if (!validators_->pixel_store_alignment.IsValid(param)) {
+            SetGLError(GL_INVALID_VALUE,
+                       "glPixelSTore: param GL_INVALID_VALUE");
+            return error::kNoError;
+        }
+    default:
+        break;
   }
   glPixelStorei(pname, param);
   switch (pname) {
   case GL_PACK_ALIGNMENT:
       pack_alignment_ = param;
       break;
+  case GL_PACK_REVERSE_ROW_ORDER_ANGLE:
+      break;
   case GL_UNPACK_ALIGNMENT:
       unpack_alignment_ = param;
       break;