gpu, cmaa: improve |do_copy| condition logic

gpu/command_buffer/service/gles2_cmd_apply_framebuffer_attachment_cmaa_intel.cc

Index: gpu/command_buffer/service/gles2_cmd_apply_framebuffer_attachment_cmaa_intel.cc
diff --git a/gpu/command_buffer/service/gles2_cmd_apply_framebuffer_attachment_cmaa_intel.cc b/gpu/command_buffer/service/gles2_cmd_apply_framebuffer_attachment_cmaa_intel.cc
index a8d5e4354b29a22f14c719c7f4176c9c64e9f366..eca067cee84c79ff48aa1ceab8a7af5b0f9d3c97 100644
--- a/gpu/command_buffer/service/gles2_cmd_apply_framebuffer_attachment_cmaa_intel.cc
+++ b/gpu/command_buffer/service/gles2_cmd_apply_framebuffer_attachment_cmaa_intel.cc
@@ -8,6 +8,7 @@
 #include "gpu/command_buffer/service/framebuffer_manager.h"
 #include "gpu/command_buffer/service/gles2_cmd_copy_texture_chromium.h"
 #include "gpu/command_buffer/service/gles2_cmd_decoder.h"
+#include "gpu/command_buffer/service/texture_manager.h"
 #include "ui/gl/gl_context.h"
 #include "ui/gl/gl_gl_api_implementation.h"
 #include "ui/gl/gl_version_info.h"
@@ -241,7 +242,11 @@ void ApplyFramebufferAttachmentCMAAINTELResourceManager::
 
       // CMAA internally expects GL_RGBA8 textures.
       // Process using a GL_RGBA8 copy if this is not the case.
-      bool do_copy = internal_format != GL_RGBA8;
+      const bool rgba_immutable =
+          attachment->IsTextureAttachmentImmutable() &&

[piman, 2016/12/02 20:36:46]

Well, you already know you have a texture attachment, so, rather than adding an
extra API, why don't you grab the TextureRef/Texture from the TextureManager,
and have access to all fields that you may need (e.g. you probably also want to
check that if internal_format == GL_RGBA, that type == GL_UNSIGNED_BYTE, because
it could be e.g. GL_FLOAT or GL_HALF_FLOAT instead).

[dshwang, 2016/12/02 23:40:24]

We cannot get TextureRef/Texture from Framebuffer::Attachemnt. New patch set
added GetTexture(), instead of ad-hoc IsTextureAttachmentImmutable().
As immutable texture is only allowed, this code needs to know only
internal_format.

void glTexStorage2D(GLenum target, GLsizei levels, GLenum internalformat,
GLsizei width, GLsizei height);

[piman, 2016/12/05 20:07:08]

attachment->object_name() gives you the client texture id.
TextureManager::GetTexture(client_id) will give you the TextureRef.

[dshwang, 2016/12/09 03:23:27]

Done. Thank you for educating :)

+          TextureManager::ExtractFormatFromStorageFormat(internal_format) ==
+              GL_RGBA;
+      const bool do_copy = !rgba_immutable;
 
       // CMAA Effect
       if (do_copy) {