Add support for GL_CHROMIUM_consistent_uniform_locations

gpu/command_buffer/common/gles2_cmd_utils.cc

Index: gpu/command_buffer/common/gles2_cmd_utils.cc
diff --git a/gpu/command_buffer/common/gles2_cmd_utils.cc b/gpu/command_buffer/common/gles2_cmd_utils.cc
index ea0bd7387487462c7ef9b953fcb2bffd739491d8..b4afb9ff7be6ac90c793c631f0e3b2e8d5ad9d8a 100644
--- a/gpu/command_buffer/common/gles2_cmd_utils.cc
+++ b/gpu/command_buffer/common/gles2_cmd_utils.cc
@@ -758,6 +758,29 @@ bool ContextCreationAttribParser::Parse(const std::vector<int32>& attribs) {
   return true;
 }
 
+// Swizzles the locations to prevent developers from assuming they
+// can do math on uniforms. According to the OpenGL ES 2.0 spec
+// the location of "someuniform[1]" is not 'n' more than "someuniform[0]".

[apatrick_chromium, 2012/06/18 18:58:03]

nit: [1]->[n]

+static int32 Swizzle(int32 location) {
+  return (location & 0xF0000000U) |
+         ((location & 0x0AAAAAAAU) >> 1) |
+         ((location & 0x05555555U) << 1);
+}
+
+// Adds uniform_swizzle_ to prevent developers from assuming that locations are
+// always the same across GPUs and drivers.
+int32 GLES2Util::SwizzleLocation(int32 v) {
+  return v < 0 ? v : Swizzle(v);
+}
+
+int32 GLES2Util::UnswizzleLocation(int32 v) {
+  return v < 0 ? v : Swizzle(v);
+}
+
+int32 GLES2Util::MakeFakeLocation(int32 index, int32 element) {
+  return index + element * 0x10000;
+}
+
 #include "../common/gles2_cmd_utils_implementation_autogen.h"
 
 }  // namespace gles2