Adds support for EXT_framebuffer_multisample...

gpu/command_buffer/client/gles2_implementation_autogen.h

Index: gpu/command_buffer/client/gles2_implementation_autogen.h
===================================================================
--- gpu/command_buffer/client/gles2_implementation_autogen.h	(revision 56887)
+++ gpu/command_buffer/client/gles2_implementation_autogen.h	(working copy)
@@ -770,6 +770,35 @@
   helper_->Viewport(x, y, width, height);
 }
 
+void BlitFramebufferEXT(
+    GLint srcX0, GLint srcY0, GLint srcX1, GLint srcY1, GLint dstX0,
+    GLint dstY0, GLint dstX1, GLint dstY1, GLbitfield mask, GLenum filter) {
+  helper_->BlitFramebufferEXT(
+      srcX0, srcY0, srcX1, srcY1, dstX0, dstY0, dstX1, dstY1, mask, filter);
+}
+
+void RenderbufferStorageMultisampleEXT(
+    GLenum target, GLsizei samples, GLenum internalformat, GLsizei width,
+    GLsizei height) {
+  if (samples < 0) {
+    SetGLError(
+        GL_INVALID_VALUE, "glRenderbufferStorageMultisampleEXT: samples < 0");
+    return;
+  }
+  if (width < 0) {
+    SetGLError(
+        GL_INVALID_VALUE, "glRenderbufferStorageMultisampleEXT: width < 0");
+    return;
+  }
+  if (height < 0) {
+    SetGLError(
+        GL_INVALID_VALUE, "glRenderbufferStorageMultisampleEXT: height < 0");
+    return;
+  }
+  helper_->RenderbufferStorageMultisampleEXT(
+      target, samples, internalformat, width, height);
+}
+
 void SwapBuffers();
 
 GLuint GetMaxValueInBuffer(