Reland of Revert of gpu: introduce glCopySubTextureCHROMIUM (patchset #1 id:1 of https://codereview…

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 6b9a51967a0f2e42d41dc192585a4160236ef923..7efc37654f02a0db1edee86ebae454002f544591 100644
--- a/ui/gl/gl_image_memory.cc
+++ b/ui/gl/gl_image_memory.cc
@@ -264,7 +264,7 @@ bool GLImageMemory::BindTexImage(unsigned target) {
   return true;
 }
 
-bool GLImageMemory::CopyTexImage(unsigned target) {
+bool GLImageMemory::CopyTexSubImage(unsigned target, int xoffset, int yoffset) {
   TRACE_EVENT0("gpu", "GLImageMemory::CopyTexImage");
 
   // GL_TEXTURE_EXTERNAL_OES is not a supported CopyTexImage target.
@@ -275,17 +275,13 @@ bool GLImageMemory::CopyTexImage(unsigned target) {
   if (IsCompressedFormat(format_)) {
     glCompressedTexSubImage2D(target,
                               0,  // level
-                              0,  // x-offset
-                              0,  // y-offset
-                              size_.width(), size_.height(),
+                              xoffset, yoffset, size_.width(), size_.height(),
                               DataFormat(format_), SizeInBytes(size_, format_),
                               memory_);
   } else {
     glTexSubImage2D(target, 0,  // level
-                    0,          // x
-                    0,          // y
-                    size_.width(), size_.height(), DataFormat(format_),
-                    DataType(format_), memory_);
+                    xoffset, yoffset, size_.width(), size_.height(),
+                    DataFormat(format_), DataType(format_), memory_);
   }
 
   return true;