ozone: ClientPixmapManager passes VGEM fd from browser to renderer.

ui/ozone/platform/drm/common/client_native_pixmap_factory_gbm.cc

Index: ui/ozone/platform/drm/common/client_native_pixmap_factory_gbm.cc
diff --git a/ui/ozone/platform/drm/common/client_native_pixmap_factory_gbm.cc b/ui/ozone/platform/drm/common/client_native_pixmap_factory_gbm.cc
index 76a94b89ad9f65b9fa74ae900072f02b7a85dc65..d674ed5c4246b8352dce782068a72e0c2890afef 100644
--- a/ui/ozone/platform/drm/common/client_native_pixmap_factory_gbm.cc
+++ b/ui/ozone/platform/drm/common/client_native_pixmap_factory_gbm.cc
@@ -4,12 +4,12 @@
 
 #include "ui/ozone/platform/drm/common/client_native_pixmap_factory_gbm.h"
 
-#include "base/file_descriptor_posix.h"
 #include "ui/gfx/native_pixmap_handle_ozone.h"
 #include "ui/ozone/public/client_native_pixmap_factory.h"
 
 #if defined(USE_VGEM_MAP)
-#include <fcntl.h>
+#include "base/synchronization/waitable_event.h"
+#include "base/threading/thread_checker.h"
 #include "ui/ozone/platform/drm/gpu/client_native_pixmap_vgem.h"
 #endif
 
@@ -32,18 +32,18 @@ class ClientNativePixmapGbm : public ClientNativePixmap {
 
 class ClientNativePixmapFactoryGbm : public ClientNativePixmapFactory {
  public:
-  ClientNativePixmapFactoryGbm() {
-#if defined(USE_VGEM_MAP)
-    // TODO(dshwang): remove ad-hoc file open. crrev.com/1248713002
-    static const char kVgemPath[] = "/dev/dri/renderD129";
-    int vgem_fd = open(kVgemPath, O_RDWR | O_CLOEXEC);
-    vgem_fd_.reset(vgem_fd);
-    DCHECK_GE(vgem_fd_.get(), 0) << "Failed to open: " << kVgemPath;
-#endif
-  }
+  ClientNativePixmapFactoryGbm() : set_vgem_fd_event_(true, false) {}
   ~ClientNativePixmapFactoryGbm() override {}
 
   // ClientNativePixmapFactory:
+  void Initialize(base::ScopedFD device_fd) override {
+#if defined(USE_VGEM_MAP)
+    DCHECK_LT(vgem_fd_.get(), 0);
+    vgem_fd_ = device_fd.Pass();
+    set_vgem_fd_thread_checker_.reset(new base::ThreadChecker());
+    set_vgem_fd_event_.Signal();
+#endif
+  }
   std::vector<Configuration> GetSupportedConfigurations() const override {
     const Configuration kConfigurations[] = {
         {gfx::BufferFormat::BGRA_8888, gfx::BufferUsage::SCANOUT},
@@ -65,6 +65,11 @@ class ClientNativePixmapFactoryGbm : public ClientNativePixmapFactory {
     switch (usage) {
       case gfx::BufferUsage::MAP:
 #if defined(USE_VGEM_MAP)
+        // A valid |vgem_fd_| is required to acquire a VGEM bo. This will wait
+        // for a valid |vgem_fd_| if one has not yet been set.
+        set_vgem_fd_event_.Wait();
+        DCHECK(!set_vgem_fd_thread_checker_->CalledOnValidThread());
+        DCHECK_GE(vgem_fd_.get(), 0);
         return ClientNativePixmapVgem::ImportFromDmabuf(
             vgem_fd_.get(), scoped_fd.get(), size, handle.stride);
 #endif
@@ -84,6 +89,8 @@ class ClientNativePixmapFactoryGbm : public ClientNativePixmapFactory {
  private:
 #if defined(USE_VGEM_MAP)
   base::ScopedFD vgem_fd_;
+  scoped_ptr<base::ThreadChecker> set_vgem_fd_thread_checker_;
+  base::WaitableEvent set_vgem_fd_event_;
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(ClientNativePixmapFactoryGbm);