Propagate supported scanout formats from driver to SurfaceFactoryOzone.

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

Index: ui/ozone/platform/drm/gpu/gbm_surface_factory.cc
diff --git a/ui/ozone/platform/drm/gpu/gbm_surface_factory.cc b/ui/ozone/platform/drm/gpu/gbm_surface_factory.cc
index fb9157bc9a8c451910725be872aa1cf7b80d56a4..28ba6b1b1148e399b812223ca5ac27760592c78e 100644
--- a/ui/ozone/platform/drm/gpu/gbm_surface_factory.cc
+++ b/ui/ozone/platform/drm/gpu/gbm_surface_factory.cc
@@ -10,6 +10,7 @@
 #include "build/build_config.h"
 #include "third_party/khronos/EGL/egl.h"
 #include "ui/ozone/common/egl_util.h"
+#include "ui/ozone/platform/drm/common/drm_util.h"
 #include "ui/ozone/platform/drm/gpu/drm_thread_proxy.h"
 #include "ui/ozone/platform/drm/gpu/drm_window_proxy.h"
 #include "ui/ozone/platform/drm/gpu/gbm_buffer.h"
@@ -103,6 +104,33 @@ GbmSurfaceFactory::CreateSurfacelessEGLSurfaceForWidget(
       new GbmSurfaceless(drm_thread_->CreateDrmWindowProxy(widget), this));
 }
 
+bool GbmSurfaceFactory::GetSupportedFormats(

[spang, 2016/01/20 18:52:24]

Why does this take a usage parameter?

This is checking formats supported by the display controller, so it's only
relevant for scanout.

It seems like 

  std::vector<gfx::BufferFormat> GetScanoutFormats();

is what you want.

But it's concerning that this API is not parameterized by display device. It'll
break if some secondary device doesn't have all the formats of the primary
device, right?

[william.xie, 2016/01/21 02:14:02]

Thanks Michael, I documented the concern in the API header file to notify the
user be careful for that. 

+    gfx::BufferUsage buffer_usage,
+    std::vector<gfx::BufferFormat>* support_formats) {
+  auto it = support_formats_map_.find(buffer_usage);
+  if (it != support_formats_map_.end()) {
+    *support_formats = it->second;
+    return true;
+  }
+
+  switch (buffer_usage) {
+    case gfx::BufferUsage::SCANOUT:
+      if (drm_thread_ != nullptr) {
+        std::vector<uint32_t> fourcc_formats;
+        drm_thread_->GetSupportedFormats(&fourcc_formats);
+        for (auto& fourcc : fourcc_formats)
+          support_formats->push_back(GetBufferFormatFromFourCCFormat(fourcc));
+        support_formats_map_.insert(
+            std::make_pair(buffer_usage, *support_formats));
+        return true;
+      }
+    default:
+      return false;
+  }
+
+  return false;
+}
+
 scoped_refptr<ui::NativePixmap> GbmSurfaceFactory::CreateNativePixmap(
     gfx::AcceleratedWidget widget,
     gfx::Size size,