glBindTexImage2DCHROMIUM should retain pixel format.

ui/gl/gl_image_memory.cc

Index: ui/gl/gl_image_memory.cc
diff --git a/ui/gl/gl_image_memory.cc b/ui/gl/gl_image_memory.cc
index 56301dfab6c953acc677b27ea74f2259efcb79d7..a10153b94ffcdd239faf2e4a5782786e1a4ef6cc 100644
--- a/ui/gl/gl_image_memory.cc
+++ b/ui/gl/gl_image_memory.cc
@@ -238,6 +238,10 @@ Size GLImageMemory::GetSize() {
   return size_;
 }
 
+unsigned GLImageMemory::GetFormat() {
+  return internalformat_;
+}
+
 bool GLImageMemory::BindTexImage(unsigned target) {
   if (target_ && target_ != target) {
     LOG(ERROR) << "GLImage can only be bound to one target";