gpu: Add async pixel transfer interface, stub and tests.

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 2ec1e96e4a4fbe30f2a81b4996002b4cd88976d3..819f2aaeca9c381d161bc6280be321ee9d7330f4 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -55,6 +55,7 @@
 #include "gpu/command_buffer/service/texture_manager.h"
 #include "gpu/command_buffer/service/vertex_attrib_manager.h"
 #include "gpu/command_buffer/service/vertex_array_manager.h"
+#include "ui/gl/async_pixel_transfer_delegate.h"
 #include "ui/gl/gl_image.h"
 #include "ui/gl/gl_implementation.h"
 #include "ui/gl/gl_surface.h"
@@ -9399,9 +9400,43 @@ error::Error GLES2DecoderImpl::HandleAsyncTexSubImage2DCHROMIUM(
     return error::kOutOfBounds;
   }
 
-  // TODO(epenner): Do this via an async task.
-  DoTexSubImage2D(
-      target, level, xoffset, yoffset, width, height, format, type, pixels);
+  // We only support async uploads to 2D textures for now.
+  if (target != GL_TEXTURE_2D) {
+    SetGLErrorInvalidEnum("glTexSubImage2D", type, "type");

[greggman, 2012/12/05 02:23:42]

s/glTexSubImage2D/glAsyncTexSubImage2DCHROMIUM/

here and a bunch of other places

[epenner, 2012/12/08 03:15:03]

Done.

+    return error::kNoError;
+  }
+
+  // We only support uploads to level zero for now.
+  if (level != 0) {
+    SetGLError(GL_INVALID_VALUE, "glTexSubImage2D", "level != 0");
+    return error::kNoError;
+  }
+
+  const TextureUnit& unit = state_.texture_units[state_.active_texture_unit];
+  TextureManager::TextureInfo* info = unit.bound_texture_2d;
+
+  // TODO(epenner): We should really do this level clear as part of the

[apatrick, 2012/12/03 21:23:59]

It might be a bit tricky to synchronize that. Maybe it's okay to do it here if
it is known to be rare. Let's see what gman thinks.

[epennerAtGoogle, 2012/12/03 22:48:45]

Hmm.. You are right. If we keep the clear here, then everything is safe.  Since
the cost can easily be avoided, best to just keep it here.

[epennerAtGoogle, 2012/12/04 19:56:48]

Done.

+  // async upload. However this clear is rarely needed anyway.
+  GLsizei tex_width = 0;
+  GLsizei tex_height = 0;
+  bool ok = info->GetLevelSize(target, level, &tex_width, &tex_height);
+  DCHECK(ok);
+  if (xoffset != 0 || yoffset != 0 ||
+      width != tex_width || height != tex_height) {
+    if (!texture_manager()->ClearTextureLevel(this, info, target, level)) {
+      SetGLError(GL_OUT_OF_MEMORY, "glTexSubImage2D", "dimensions too big");
+      return error::kNoError;
+    }
+  }
+
+  // TODO(epenner): The level is technically not cleared yet!
+  // However we need to mark it as cleared to use the texture.
+  // It looks like we need to mark as cleared in an async reply.
+  texture_manager()->SetLevelCleared(info, target, level);
+  gfx::AsyncPixelTransferDelegate::Get()->AsyncTexSubImage2D(

[greggman, 2012/12/05 02:23:42]

I thought singletons are discouraged in Chromium? Other than the driver setup
I'm not aware of any other singleton's in the gpu code. Is there a reason for
this exception? It's certainly easier then passing in or setting some
AsyncPixelTransferManager but it also makes it harder to mock for testing.

[epenner, 2012/12/05 04:01:54]

It's one of my TODOs. Yeah I wasn't sure initially where to put it and I still
haven't investigated it. If you have a good home in mind I'm all ears. It needs
to exist at a pretty high level in the GPU process so multiple don't get
created.

+      info->AsyncTransferState(), target, level, xoffset, yoffset,
+      width, height, format, type, pixels);
+
   return error::kNoError;
 }