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

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

Index: ui/ozone/platform/drm/gpu/gbm_buffer_base.cc
diff --git a/ui/ozone/platform/drm/gpu/gbm_buffer_base.cc b/ui/ozone/platform/drm/gpu/gbm_buffer_base.cc
index 5f27c51e7e9f04c1625622f7384e6f4765448932..610249a6920e24fff472c418c3907e0eaaae67fc 100644
--- a/ui/ozone/platform/drm/gpu/gbm_buffer_base.cc
+++ b/ui/ozone/platform/drm/gpu/gbm_buffer_base.cc
@@ -14,10 +14,11 @@ namespace ui {
 GbmBufferBase::GbmBufferBase(const scoped_refptr<DrmDevice>& drm,
                              gbm_bo* bo,
                              bool scanout)
-    : drm_(drm), bo_(bo) {
+    : drm_(drm), bo_(bo), fb_pixel_format_(gbm_bo_get_format(bo)) {

[kalyank, 2015/12/11 04:57:41]

Unless its a scanout buffer and the buffer is registered, fb_pixel_format_should
just return 0. We should just leave this as before.

[dshwang, 2015/12/11 07:17:32]

Ok, agree.
To clarify, rename it to framebuffer_pixel_format_;

   if (scanout) {
-    fb_pixel_format_ = gbm_bo_get_format(bo);
-    if (fb_pixel_format_ == GBM_FORMAT_ARGB8888)
+    // Currently, drm supports 24 bitcolordepth for hardware overlay.
+    if (fb_pixel_format_ == GBM_FORMAT_ARGB8888 ||
+        fb_pixel_format_ == GBM_FORMAT_ABGR8888)

[kalyank, 2015/12/11 04:57:41]

ABGR, is this format going to be used ?

[dshwang, 2015/12/11 07:17:32]

ABGR is not used by chrome. However, ozone gbm supports ABGR scanout buffer, and
content_unittests covers if it works.
https://code.google.com/p/chromium/codesearch#chromium/src/ui/ozone/platform/...

[kalyank, 2015/12/11 19:07:12]

Only BGRA and RGBA are advertised. In BGRA case, format has to be
GBM_FORMAT_BGRX8888.

[dshwang, 2015/12/13 05:34:43]

Got it. New CL supports both BGRX8888 and RGBX8888.

       fb_pixel_format_ = GBM_FORMAT_XRGB8888;
 
     // For now, we only support XRGB and UYVY format.