Enable sync allocation of GpuMemoryBuffers from the browser process.

content/common/gpu/client/gpu_memory_buffer_impl_ozone_native_buffer.cc

Index: content/common/gpu/client/gpu_memory_buffer_impl_ozone_native_buffer.cc
diff --git a/content/common/gpu/client/gpu_memory_buffer_impl_ozone_native_buffer.cc b/content/common/gpu/client/gpu_memory_buffer_impl_ozone_native_buffer.cc
index fe2681bf051df7b4e5efe3aef6b7db461204fe2e..560eef44610cc1bb9a7e0cb73bf72dbdbe9b68ed 100644
--- a/content/common/gpu/client/gpu_memory_buffer_impl_ozone_native_buffer.cc
+++ b/content/common/gpu/client/gpu_memory_buffer_impl_ozone_native_buffer.cc
@@ -14,6 +14,15 @@ namespace {
 
 base::StaticAtomicSequenceNumber g_next_buffer_id;
 
+void AllocatedOzoneNativeBuffer(
+    const gfx::Size& size,
+    unsigned internalformat,
+    const GpuMemoryBufferImpl::CreationCallback& callback,
+    const gfx::GpuMemoryBufferHandle& handle) {
+  callback.Run(
+      GpuMemoryBufferImpl::CreateFromHandle(handle, size, internalformat));
+}
+
 }  // namespace
 
 GpuMemoryBufferImplOzoneNativeBuffer::GpuMemoryBufferImplOzoneNativeBuffer(
@@ -33,8 +42,7 @@ void GpuMemoryBufferImplOzoneNativeBuffer::AllocateOzoneNativeBufferForChildId(
     int child_id,
     const AllocationCallback& callback) {
   gfx::GpuMemoryBufferHandle handle;
-  // +1 ensures we always get non-zero IDs.
-  handle.global_id.primary_id = g_next_buffer_id.GetNext() + 1;
+  handle.global_id.primary_id = g_next_buffer_id.GetNext();
   handle.global_id.secondary_id = child_id;
   handle.type = gfx::OZONE_NATIVE_BUFFER;
   GpuMemoryBufferFactoryHost::GetInstance()->CreateGpuMemoryBuffer(
@@ -46,6 +54,20 @@ void GpuMemoryBufferImplOzoneNativeBuffer::AllocateOzoneNativeBufferForChildId(
 }
 
 // static
+void GpuMemoryBufferImplOzoneNativeBuffer::Create(

[reveman, 2014/09/09 23:17:54]

nit: please order the functions as GpuMemoryBufferImpl. Create,
Allocate*ForChild...

[alexst (slow to review), 2014/09/10 01:57:49]

Done.

+    const gfx::Size& size,
+    unsigned internalformat,
+    unsigned usage,
+    const CreationCallback& callback) {
+  GpuMemoryBufferImplOzoneNativeBuffer::AllocateOzoneNativeBufferForChildId(

[reveman, 2014/09/09 23:17:54]

Not a fan of using a function called *ForChildId here. This is not allocating a
buffer for a child process. It's allocating a buffer for in-process usage, or
for usage by the same client id (note: not child id) as client making the
allocation request.

I think it's fine to use 0 as a unique value for secondary_id to indicate that
it should be owned by the process sending the request or to indicate that the
client with client_id=0 should own it. Not sure we should be making the
assumption that the current process has client_id=0 from this code though..

So I don't think we should be using AllocateOzoneNativeBufferForChildId here but
GpuMemoryBufferFactoryHost::CreateGpuMemoryBuffer directly instead. Maybe you
could have the GPU process fill in the correct client_id to avoid the assumption
that the process using this API has client_id=0.

[alexst (slow to review), 2014/09/10 01:57:49]

I just used it as a shortcut, refactored to call
GpuMemoryBufferFactoryHost::CreateGpuMemoryBuffer directly. I used
secondary_id=0 to indicate in-process use.

+      size,
+      internalformat,
+      usage,
+      0,
+      base::Bind(&AllocatedOzoneNativeBuffer, size, internalformat, callback));
+}
+
+// static
 bool GpuMemoryBufferImplOzoneNativeBuffer::IsFormatSupported(
     unsigned internalformat) {
   switch (internalformat) {