gpu: introduce glCopySubTextureCHROMIUM

gpu/GLES2/extensions/CHROMIUM/CHROMIUM_copy_texture.txt

Index: gpu/GLES2/extensions/CHROMIUM/CHROMIUM_copy_texture.txt
diff --git a/gpu/GLES2/extensions/CHROMIUM/CHROMIUM_copy_texture.txt b/gpu/GLES2/extensions/CHROMIUM/CHROMIUM_copy_texture.txt
index ad9ca689ca90303ffa3c9342e3d70894ef7a5719..6845991854865ceba28f770a0abfc1a66c92c73a 100644
--- a/gpu/GLES2/extensions/CHROMIUM/CHROMIUM_copy_texture.txt
+++ b/gpu/GLES2/extensions/CHROMIUM/CHROMIUM_copy_texture.txt
@@ -36,15 +36,18 @@ Overview
 
 New Procedures and Functions
 
-    void glCopyTextureCHROMIUM (GLenum target, GLenum source_id,
-                                GLenum dest_id, GLint level,
-                                GLint internal_format, GLenum dest_type)
+    The command
 
-    Copies the contents of texture referred to by <source_id> to texture
-    <dest_id>.
+        void glCopyTextureCHROMIUM (GLenum target, GLenum source_id,
+                                    GLenum dest_id,
+                                    GLint internal_format, GLenum dest_type)
 
-    Texture level 0 is copied from the source image to level <level> of the
-    destination texture. The level parameter must be 0 at present.
+    Copies the contents of texture referred to by <source_id> to <dest_id>
+    texture. If <source_id> texture is not defined or has different dimension
+    to <dest_id> texture, define <source_id> texture same to <dest_id> texture.
+
+    Texture level 0 is copied from the source image to level 0 of the
+    destination texture.
 
     The internal format of the destination texture is converted to that
     specified by <internal_format>. Must be one of the following symbolic
@@ -87,8 +90,37 @@ New Procedures and Functions
     been bound as GL_TEXTURE_2D, GL_TEXTURE_RECTANGLE_ARB or
     GL_TEXTURE_EXTERNAL_OES objects.
 
-    INVALID_VALUE is generated if <level> is not a valid level of the
-    destination texture, or if level 0 of the source texture is not defined.
+    INVALID_VALUE is generated if level 0 of the source texture is not defined.
+
+    The command
+
+        void glCopySubTextureCHROMIUM (GLenum target, GLenum source_id,
+                                       GLenum dest_id,
+                                       GLint xoffset, GLint yoffset)
+
+    Copies the sub contents of texture referred to by <source_id> to <dest_id>
+    texture without redefining <dest_id> texture.
+
+    See CopyTextureCHROMIUM for the interpretation of the <target> arguments.
+
+    <xoffset> and <yoffset> specify a texel offset in the x and y direction
+    respectively within the destination texture.
+
+    INVALID_OPERATION is generated if source internal_format and destination
+    internal_format are not one of the valid formats described above.
+
+    INVALID_VALUE is generated if <target> is not GL_TEXTURE_2D.
+
+    INVALID_OPERATION is generated if the destination texture has not been
+    defined.
+
+    INVALID_VALUE is generated if level 0 of the source texture or
+    the destination texture is not defined.
+
+    INVALID_VALUE is generated if <xoffset> < 0 , or <yoffset> < 0.
+
+    INVALID_VALUE is generated if (<xoffset> + source_width) > dest_width,
+    or (<yoffset> + source_height) > dest_height.
 
 Errors