ozone: set the right GBM_BO_ flags

minigbm doesn't allow to pass no flags to gbm_bo_create(). GBM_BO_USE_TEXTURING
implies texture, so use GBM_BO_USE_TEXTURING to create texture buffer.

GBM_BO_USE_TEXTURING implies GPU_READ. GBM_BO_USE_RENDERING implies GPU_WRITE.
BufferUsage::SCANOUT needs both of them because it implies GPU_READ_WRITE.

TEST=run chrome on amd64-generic
BUG=683347

Change-Id: I7431be6f5b4a8d95e6be11d86cfbf0c14b919668
Reviewed-on: https://chromium-review.googlesource.com/549095Reviewed-by: Daniel Nicoara <dnicoara@chromium.org>
Reviewed-by: Daniele Castagna <dcastagna@chromium.org>
Reviewed-by: David Reveman <reveman@chromium.org>
Reviewed-by: Stéphane Marchesin <marcheu@chromium.org>
Reviewed-by: Dongseong Hwang <dongseong.hwang@intel.com>
Commit-Queue: Dongseong Hwang <dongseong.hwang@intel.com>
Cr-Commit-Position: refs/heads/master@{#488709}

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

@@ -117,16 +117,17 @@ void DrmThread::CreateBuffer(gfx::AcceleratedWidget widget,
   uint32_t flags = 0;
   switch (usage) {
     case gfx::BufferUsage::GPU_READ:
+      flags = GBM_BO_USE_TEXTURING;
       break;
     case gfx::BufferUsage::SCANOUT:
-      flags = GBM_BO_USE_SCANOUT | GBM_BO_USE_RENDERING;
+      flags = GBM_BO_USE_RENDERING | GBM_BO_USE_SCANOUT | GBM_BO_USE_TEXTURING;
       break;
     case gfx::BufferUsage::SCANOUT_CPU_READ_WRITE:
-      flags = GBM_BO_USE_SCANOUT | GBM_BO_USE_LINEAR;
+      flags = GBM_BO_USE_LINEAR | GBM_BO_USE_SCANOUT | GBM_BO_USE_TEXTURING;
       break;
     case gfx::BufferUsage::GPU_READ_CPU_READ_WRITE:
     case gfx::BufferUsage::GPU_READ_CPU_READ_WRITE_PERSISTENT:
-      flags = GBM_BO_USE_LINEAR;
+      flags = GBM_BO_USE_LINEAR | GBM_BO_USE_TEXTURING;
       break;
   }