gfx: Add GpuFence::Wait() method

Provide a GpuFence::Wait() method to hide the implementation details of
waiting for a GpuFence object.

Bug: 828393
Change-Id: I2153ebcb4b8cca6bb43c827fb0a9740f6a6cc221
Reviewed-on: https://chromium-review.googlesource.com/1021513Reviewed-by: David Reveman <reveman@chromium.org>
Reviewed-by: Antoine Labour <piman@chromium.org>
Commit-Queue: Daniele Castagna <dcastagna@chromium.org>
Cr-Commit-Position: refs/heads/master@{#559292}

ui/gfx/BUILD.gn

@@ -567,6 +567,10 @@ source_set("memory_buffer_sources") {
     deps += [ "//third_party/libdrm" ]
   }
 
+  if (is_linux || is_android) {
+    deps += [ "//third_party/libsync" ]
+  }
+
   if (is_mac) {
     sources += [
       "mac/io_surface.cc",

ui/gfx/gpu_fence.cc

@@ -6,6 +6,10 @@
 
 #include "base/logging.h"
 
+#if defined(OS_LINUX) || defined(OS_ANDROID)
+#include <sync/sync.h>
+#endif
+
 namespace gfx {
 
 GpuFence::GpuFence(const GpuFenceHandle& handle) : type_(handle.type) {
@@ -51,4 +55,22 @@ GpuFence* GpuFence::FromClientGpuFence(ClientGpuFence gpu_fence) {
   return reinterpret_cast<GpuFence*>(gpu_fence);
 }
 
+void GpuFence::Wait() {
+  switch (type_) {
+    case GpuFenceHandleType::kEmpty:
+      break;
+    case GpuFenceHandleType::kAndroidNativeFenceSync:
+#if defined(OS_LINUX) || defined(OS_ANDROID)
+      static const int kInfiniteSyncWaitTimeout = -1;
+      DCHECK_GE(owned_fd_.get(), 0);
+      if (sync_wait(owned_fd_.get(), kInfiniteSyncWaitTimeout) < 0) {
+        LOG(FATAL) << "Failed while waiting for gpu fence fd";
+      }
+#else
+      NOTREACHED();
+#endif
+      break;
+  }
+}
+
 }  // namespace gfx

ui/gfx/gpu_fence.h

@@ -32,6 +32,9 @@ class GFX_EXPORT GpuFence {
   ClientGpuFence AsClientGpuFence();
   static GpuFence* FromClientGpuFence(ClientGpuFence gpu_fence);
 
+  // Wait for the GpuFence to become ready.
+  void Wait();
+
  private:
   gfx::GpuFenceHandleType type_;
 #if defined(OS_POSIX)