Make invalidateFramebuffer no-op for DEPTH_STENCIL attachment

gpu/command_buffer/service/gles2_cmd_decoder.cc

Index: gpu/command_buffer/service/gles2_cmd_decoder.cc
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder.cc b/gpu/command_buffer/service/gles2_cmd_decoder.cc
index 6df7f6a2f816a89bb6e37149101e0a60c27a2da4..21b4c80ac5b4e6a2dc03901803b7e2bcf2d5b91a 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -6981,7 +6981,12 @@ void GLES2DecoderImpl::DoFramebufferRenderbuffer(
   }
   GLenum error = LOCAL_PEEK_GL_ERROR("glFramebufferRenderbuffer");
   if (error == GL_NO_ERROR) {
-    framebuffer->AttachRenderbuffer(attachment, renderbuffer);
+    if (attachment == GL_DEPTH_STENCIL_ATTACHMENT) {
+      framebuffer->AttachRenderbuffer(GL_DEPTH_ATTACHMENT, renderbuffer);
+      framebuffer->AttachRenderbuffer(GL_STENCIL_ATTACHMENT, renderbuffer);
+    } else {
+      framebuffer->AttachRenderbuffer(attachment, renderbuffer);
+    }
   }
   if (framebuffer == framebuffer_state_.bound_draw_framebuffer.get()) {
     framebuffer_state_.clear_state_dirty = true;
@@ -11202,8 +11207,18 @@ bool GLES2DecoderImpl::ClearLevel(Texture* texture,
     state_.SetDeviceDepthMask(GL_TRUE);
     state_.SetDeviceCapabilityState(GL_SCISSOR_TEST, true);
     glScissor(xoffset, yoffset, width, height);
-    glClear(GL_DEPTH_BUFFER_BIT | (have_stencil ? GL_STENCIL_BUFFER_BIT : 0));
-
+    if (format != GL_DEPTH_STENCIL) {
+      glClear(GL_DEPTH_BUFFER_BIT | (have_stencil ? GL_STENCIL_BUFFER_BIT : 0));
+    } else {
+      // When format is DEPTH_STENCIL, only clear the uncleared part.
+      GLbitfield clear_bits = 0;
+      if (!texture->IsLevelCleared(target, level, GL_DEPTH_ATTACHMENT))
+        clear_bits |= GL_DEPTH_BUFFER_BIT;
+      if (have_stencil && !texture->IsLevelCleared(target, level,

[qiankun, 2016/07/14 06:48:21]

new line after &&

+                                                   GL_STENCIL_ATTACHMENT))
+        clear_bits |= GL_STENCIL_BUFFER_BIT;
+      glClear(clear_bits);
+    }
     RestoreClearState();
 
     glDeleteFramebuffersEXT(1, &fb);