ozone: support gfx::BufferFormat::RGBX_8888 as a native pixmap format.

ui/ozone/platform/drm/gpu/gbm_buffer.cc

Index: ui/ozone/platform/drm/gpu/gbm_buffer.cc
diff --git a/ui/ozone/platform/drm/gpu/gbm_buffer.cc b/ui/ozone/platform/drm/gpu/gbm_buffer.cc
index b18238e893c6d21834add54e6d4a862013579af5..cfa5ab7d588779e0f261513ec5cc8734b6e7472c 100644
--- a/ui/ozone/platform/drm/gpu/gbm_buffer.cc
+++ b/ui/ozone/platform/drm/gpu/gbm_buffer.cc
@@ -31,9 +31,9 @@ namespace ui {
 
 GbmBuffer::GbmBuffer(const scoped_refptr<GbmDevice>& gbm,
                      gbm_bo* bo,
+                     gfx::BufferFormat format,
                      gfx::BufferUsage usage)
-    : GbmBufferBase(gbm, bo, usage == gfx::BufferUsage::SCANOUT),
-      usage_(usage) {}
+    : GbmBufferBase(gbm, bo, format, usage), format_(format), usage_(usage) {}
 
 GbmBuffer::~GbmBuffer() {
   if (bo())
@@ -58,7 +58,7 @@ scoped_refptr<GbmBuffer> GbmBuffer::CreateBuffer(
   if (!bo)
     return nullptr;
 
-  scoped_refptr<GbmBuffer> buffer(new GbmBuffer(gbm, bo, usage));
+  scoped_refptr<GbmBuffer> buffer(new GbmBuffer(gbm, bo, format, usage));
   if (use_scanout && !buffer->GetFramebufferId())
     return nullptr;
 
@@ -142,7 +142,7 @@ int GbmPixmap::GetDmaBufPitch() const {
 }
 
 gfx::BufferFormat GbmPixmap::GetBufferFormat() const {
-  return GetBufferFormatFromFourCCFormat(buffer_->GetFramebufferPixelFormat());
+  return buffer_->GetFormat();

[kalyank, 2015/12/15 00:55:12]

These changes now broke checks in VaapiWrapper. 
https://code.google.com/p/chromium/codesearch#chromium/src/content/common/gpu...

Expectation is to return the framebuffer format here. Perhaps have another API
like GetStorageFormat which returns the internal format and GetBufferFormat
would return the pixel format as you have done.

[dshwang, 2015/12/15 04:48:31]

Nope, VaapiWrapper requires format of dma_buf, not framebuffer, because Vaapi
wants to decode directly into dma_buf. [1][2]
[1]
https://code.google.com/p/chromium/codesearch#chromium/src/ui/ozone/platform/...
[2]
https://code.google.com/p/chromium/codesearch#chromium/src/content/common/gpu...

So it doesn't break promise with VaapiWrapper.

In addition (1), content (e.g. VaapiWrapper) should not know how ozone changes
framebuffer format internally. It's so implementation detail. If something
becomes wrong, ozone should handle it by itself. It's why I felt format changing
is a bit hackish and move the code into one place.

In addition (2), VaapiWrapper creates only BGRX_8888 and UYVY_422. When
extending more format support for Vaapi, the switch statement should be updated
at the time. VaapiWrapper is ozone client, not ozone.

 }
 
 gfx::Size GbmPixmap::GetBufferSize() const {