Add CommandBuffer::SetGetBuffer

As well as remove CommandBuffer::GetRingBuffer and
change CommandBuffer::Initialize

Before this change the service allocated and managed the command buffer.

After this change the client uses CreateTransferBuffer, GetTransferBuffer,
end potentially DeleteTransferBufffer to manage the command buffer.

Another CL will actually make the client delete the command buffer
on demand.

TEST=unit tests and run some samples and a NaCl 3D game
BUG=103989

Review URL: http://codereview.chromium.org/8566059

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@113250 0039d316-1c4b-4281-b951-d872f2087c98

15 files changed, 87 insertions, 170 deletions

diff --git a/ppapi/c/trusted/ppb_graphics_3d_trusted.h b/ppapi/c/trusted/ppb_graphics_3d_trusted.h
index d6a6481..353b6dd 100644
--- a/ppapi/c/trusted/ppb_graphics_3d_trusted.h
+++ b/ppapi/c/trusted/ppb_graphics_3d_trusted.h
@@ -59,12 +59,10 @@ struct PPB_Graphics3DTrusted {
                            const int32_t* attrib_list);
 
   // Initializes the command buffer with the given size.
-  PP_Bool (*InitCommandBuffer)(PP_Resource context_id, int32_t size);
+  PP_Bool (*InitCommandBuffer)(PP_Resource context_id);
 
-  // Gets the ring buffer for the command buffer.
-  PP_Bool (*GetRingBuffer)(PP_Resource context_id,
-                           int* shm_handle,
-                           uint32_t* shm_size);
+  // Sets the buffer used for commands.
+  PP_Bool (*SetGetBuffer)(PP_Resource context, int32_t transfer_buffer_id);
 
   // Returns the current state.
   struct PP_Graphics3DTrustedState (*GetState)(PP_Resource context);
diff --git a/ppapi/native_client/src/shared/ppapi_proxy/browser_ppb_graphics_3d_rpc_server.cc b/ppapi/native_client/src/shared/ppapi_proxy/browser_ppb_graphics_3d_rpc_server.cc
index 62ea1eb..f678be1 100644
--- a/ppapi/native_client/src/shared/ppapi_proxy/browser_ppb_graphics_3d_rpc_server.cc
+++ b/ppapi/native_client/src/shared/ppapi_proxy/browser_ppb_graphics_3d_rpc_server.cc
@@ -244,40 +244,26 @@ void PpbGraphics3DRpcServer::PPB_Graphics3DTrusted_InitCommandBuffer(
     NaClSrpcRpc* rpc,
     NaClSrpcClosure* done,
     PP_Resource resource_id,
-    int32_t size,
     int32_t* success) {
   DebugPrintf("PPB_Graphics3DTrusted_InitCommandBuffer(...) resource_id: %d\n",
       resource_id);
   NaClSrpcClosureRunner runner(done);
   rpc->result = NACL_SRPC_RESULT_APP_ERROR;
-  if ((size > kMaxAllowedBufferSize) || (size < 0))
-    return;
   *success = ppapi_proxy::PPBGraphics3DTrustedInterface()->InitCommandBuffer(
-      resource_id, size);
+      resource_id);
   rpc->result = NACL_SRPC_RESULT_OK;
 }
 
-
-void PpbGraphics3DRpcServer::PPB_Graphics3DTrusted_GetRingBuffer(
+void PpbGraphics3DRpcServer::PPB_Graphics3DTrusted_SetGetBuffer(
     NaClSrpcRpc* rpc,
     NaClSrpcClosure* done,
     PP_Resource resource_id,
-    NaClSrpcImcDescType* shm_desc,
-    int32_t* shm_size) {
-  DebugPrintf("PPB_Graphics3DTrusted_GetRingBuffer\n");
-  nacl::DescWrapperFactory factory;
-  nacl::scoped_ptr<nacl::DescWrapper> desc_wrapper;
+    int32_t transfer_buffer_id) {
+  DebugPrintf("PPB_Graphics3DTrusted_SetGetBuffer\n");
   NaClSrpcClosureRunner runner(done);
   rpc->result = NACL_SRPC_RESULT_APP_ERROR;
-
-  int native_handle = 0;
-  uint32_t native_size = 0;
-  ppapi_proxy::PPBGraphics3DTrustedInterface()->GetRingBuffer(
-      resource_id, &native_handle, &native_size);
-  desc_wrapper.reset(factory.ImportShmHandle(
-      (NaClHandle)native_handle, native_size));
-  *shm_desc = desc_wrapper->desc();
-  *shm_size = native_size;
+  ppapi_proxy::PPBGraphics3DTrustedInterface()->SetGetBuffer(
+      resource_id, transfer_buffer_id);
   rpc->result = NACL_SRPC_RESULT_OK;
 }
 
diff --git a/ppapi/native_client/src/shared/ppapi_proxy/command_buffer_nacl.cc b/ppapi/native_client/src/shared/ppapi_proxy/command_buffer_nacl.cc
index e151312..4a83a04 100644
--- a/ppapi/native_client/src/shared/ppapi_proxy/command_buffer_nacl.cc
+++ b/ppapi/native_client/src/shared/ppapi_proxy/command_buffer_nacl.cc
@@ -25,38 +25,18 @@ CommandBufferNacl::~CommandBufferNacl() {
   iface_core_->ReleaseResource(graphics_3d_);
 }
 
-bool CommandBufferNacl::Initialize(int32 size) {
+bool CommandBufferNacl::Initialize() {
   DebugPrintf("CommandBufferNacl::Initialize\n");
   int32_t success;
   NaClSrpcChannel* channel = ppapi_proxy::GetMainSrpcChannel();
   NaClSrpcError retval =
       PpbGraphics3DRpcClient::PPB_Graphics3DTrusted_InitCommandBuffer(
-          channel, graphics_3d_, size, &success);
+          channel, graphics_3d_, &success);
   DebugPrintf("CommandBufferNaCl::Initialize returned success=%s\n",
       (PP_TRUE == success) ? "TRUE" : "FALSE");
   return NACL_SRPC_RESULT_OK == retval && PP_TRUE == success;
 }
 
-gpu::Buffer CommandBufferNacl::GetRingBuffer() {
-  DebugPrintf("CommandBufferNacl::GetRingBuffer\n");
-  if (!buffer_.ptr) {
-    DebugPrintf("CommandBufferNacl::GetRingBuffer: Fetching\n");
-    int shm_handle = -1;
-    int32_t shm_size = 0;
-
-    NaClSrpcChannel* channel = ppapi_proxy::GetMainSrpcChannel();
-    NaClSrpcError retval =
-        PpbGraphics3DRpcClient::PPB_Graphics3DTrusted_GetRingBuffer(
-            channel, graphics_3d_, &shm_handle, &shm_size);
-    if (NACL_SRPC_RESULT_OK != retval) {
-      shm_handle = -1;
-    }
-    buffer_ = BufferFromShm(shm_handle, shm_size);
-  }
-
-  return buffer_;
-}
-
 gpu::CommandBuffer::State CommandBufferNacl::GetState() {
   DebugPrintf("CommandBufferNacl::GetState\n");
   PP_Graphics3DTrustedState state;
@@ -110,6 +90,13 @@ gpu::CommandBuffer::State CommandBufferNacl::FlushSync(int32 put_offset,
   return last_state_;
 }
 
+void CommandBufferNacl::SetGetBuffer(int32 transfer_buffer_id) {
+  DebugPrintf("CommandBufferNacl::SetGetBuffer\n");
+  NaClSrpcChannel* channel = ppapi_proxy::GetMainSrpcChannel();
+  PpbGraphics3DRpcClient::PPB_Graphics3DTrusted_SetGetBuffer(
+      channel, graphics_3d_, transfer_buffer_id);
+}
+
 void CommandBufferNacl::SetGetOffset(int32 get_offset) {
   DebugPrintf("CommandBufferNacl::SetGetOffset\n");
   // Not implemented by proxy.
diff --git a/ppapi/native_client/src/shared/ppapi_proxy/command_buffer_nacl.h b/ppapi/native_client/src/shared/ppapi_proxy/command_buffer_nacl.h
index a699241..20e3836 100644
--- a/ppapi/native_client/src/shared/ppapi_proxy/command_buffer_nacl.h
+++ b/ppapi/native_client/src/shared/ppapi_proxy/command_buffer_nacl.h
@@ -22,16 +22,12 @@ class CommandBufferNacl : public gpu::CommandBuffer {
   virtual ~CommandBufferNacl();
 
   // CommandBuffer implementation.
-  virtual bool Initialize(int32 size);
-  virtual bool Initialize(base::SharedMemory* buffer, int32 size) {
-    // TODO(neb): support for nacl if neccessary
-    return false;
-  }
-  virtual gpu::Buffer GetRingBuffer();
+  virtual bool Initialize();
   virtual State GetState();
   virtual State GetLastState();
   virtual void Flush(int32 put_offset);
   virtual State FlushSync(int32 put_offset, int32 last_known_get);
+  virtual void SetGetBuffer(int32 transfer_buffer_id);
   virtual void SetGetOffset(int32 get_offset);
   virtual int32 CreateTransferBuffer(size_t size, int32 id_request);
   virtual int32 RegisterTransferBuffer(base::SharedMemory* buffer,
diff --git a/ppapi/native_client/src/shared/ppapi_proxy/plugin_ppb_graphics_3d.cc b/ppapi/native_client/src/shared/ppapi_proxy/plugin_ppb_graphics_3d.cc
index c77902b..ead08dd 100644
--- a/ppapi/native_client/src/shared/ppapi_proxy/plugin_ppb_graphics_3d.cc
+++ b/ppapi/native_client/src/shared/ppapi_proxy/plugin_ppb_graphics_3d.cc
@@ -212,12 +212,9 @@ bool PluginGraphics3D::InitFromBrowserResource(PP_Resource res) {
 
   // Create and initialize the objects required to issue GLES2 calls.
   command_buffer_.reset(new CommandBufferNacl(res, PluginCore::GetInterface()));
-  if (command_buffer_->Initialize(kRingBufferSize)) {
+  if (command_buffer_->Initialize()) {
     gles2_helper_.reset(new gpu::gles2::GLES2CmdHelper(command_buffer_.get()));
-    gpu::Buffer buffer = command_buffer_->GetRingBuffer();
-    DebugPrintf("PluginGraphics3D::InitFromBrowserResource: buffer size: %d\n",
-        buffer.size);
-    if (gles2_helper_->Initialize(buffer.size)) {
+    if (gles2_helper_->Initialize(kRingBufferSize)) {
       // Request id -1 to signify 'don't care'
       int32 transfer_buffer_id =
           command_buffer_->CreateTransferBuffer(kTransferBufferSize, -1);
diff --git a/ppapi/native_client/src/shared/ppapi_proxy/ppb_graphics_3d.srpc b/ppapi/native_client/src/shared/ppapi_proxy/ppb_graphics_3d.srpc
index fe0b499..0cb9b57 100644
--- a/ppapi/native_client/src/shared/ppapi_proxy/ppb_graphics_3d.srpc
+++ b/ppapi/native_client/src/shared/ppapi_proxy/ppb_graphics_3d.srpc
@@ -77,16 +77,15 @@
           # Initialize the command buffer.
           {'name': 'PPB_Graphics3DTrusted_InitCommandBuffer',
            'inputs': [['resource_id', 'PP_Resource'],
-                      ['size', 'int32_t']
                       ],
            'outputs': [['success', 'int32_t']]  # PP_Bool
           },
-          # Get the ring buffer.
-          {'name': 'PPB_Graphics3DTrusted_GetRingBuffer',
-           'inputs': [['resource_id', 'PP_Resource']],
-           'outputs': [['shm_desc', 'handle'],
-                       ['shm_size', 'int32_t']
-                      ]
+          # Set the buffer used for commands.
+          {'name': 'PPB_Graphics3DTrusted_SetGetBuffer',
+           'inputs': [['resource_id', 'PP_Resource'],
+                      ['shm_id', 'int32_t'],
+                     ],
+           'outputs': []
           },
           # Get command buffer state.
           {'name': 'PPB_Graphics3DTrusted_GetState',
@@ -142,6 +141,6 @@
                        ['shm_size', 'int32_t']
                       ]
           },
-          # End of PPB_Graphics3DTrusted 
+          # End of PPB_Graphics3DTrusted
         ]
 }
diff --git a/ppapi/native_client/src/shared/ppapi_proxy/ppb_rpc_client.cc b/ppapi/native_client/src/shared/ppapi_proxy/ppb_rpc_client.cc
index 20ebd55..e5739ba 100644
--- a/ppapi/native_client/src/shared/ppapi_proxy/ppb_rpc_client.cc
+++ b/ppapi/native_client/src/shared/ppapi_proxy/ppb_rpc_client.cc
@@ -1435,7 +1435,6 @@ NaClSrpcError PpbGraphics3DRpcClient::PPB_Graphics3DTrusted_CreateRaw(
 NaClSrpcError PpbGraphics3DRpcClient::PPB_Graphics3DTrusted_InitCommandBuffer(
     NaClSrpcChannel* channel,
     PP_Resource resource_id,
-    int32_t size,
     int32_t* success)  {
   VCHECK(ppapi_proxy::PPBCoreInterface()->IsMainThread(),
          ("%s: PPAPI calls are not supported off the main thread\n",
@@ -1443,29 +1442,26 @@ NaClSrpcError PpbGraphics3DRpcClient::PPB_Graphics3DTrusted_InitCommandBuffer(
   NaClSrpcError retval;
   retval = NaClSrpcInvokeBySignature(
       channel,
-      "PPB_Graphics3DTrusted_InitCommandBuffer:ii:i",
+      "PPB_Graphics3DTrusted_InitCommandBuffer:i:i",
       resource_id,
-      size,
       success
   );
   return retval;
 }
 
-NaClSrpcError PpbGraphics3DRpcClient::PPB_Graphics3DTrusted_GetRingBuffer(
+NaClSrpcError PpbGraphics3DRpcClient::PPB_Graphics3DTrusted_SetGetBuffer(
     NaClSrpcChannel* channel,
     PP_Resource resource_id,
-    NaClSrpcImcDescType* shm_desc,
-    int32_t* shm_size)  {
+    int32_t transfer_buffer_id)  {
   VCHECK(ppapi_proxy::PPBCoreInterface()->IsMainThread(),
          ("%s: PPAPI calls are not supported off the main thread\n",
           __FUNCTION__));
   NaClSrpcError retval;
   retval = NaClSrpcInvokeBySignature(
       channel,
-      "PPB_Graphics3DTrusted_GetRingBuffer:i:hi",
+      "PPB_Graphics3DTrusted_SetGetBuffer:ii:",
       resource_id,
-      shm_desc,
-      shm_size
+      transfer_buffer_id
   );
   return retval;
 }
diff --git a/ppapi/native_client/src/shared/ppapi_proxy/ppb_rpc_server.cc b/ppapi/native_client/src/shared/ppapi_proxy/ppb_rpc_server.cc
index 54187d0..b40fd2d 100644
--- a/ppapi/native_client/src/shared/ppapi_proxy/ppb_rpc_server.cc
+++ b/ppapi/native_client/src/shared/ppapi_proxy/ppb_rpc_server.cc
@@ -1160,23 +1160,22 @@ static void PPB_Graphics3DTrusted_InitCommandBufferDispatcher(
       rpc,
       done,
       inputs[0]->u.ival,
-      inputs[1]->u.ival,
       &(outputs[0]->u.ival)
   );
 }
 
-static void PPB_Graphics3DTrusted_GetRingBufferDispatcher(
+static void PPB_Graphics3DTrusted_SetGetBufferDispatcher(
     NaClSrpcRpc* rpc,
     NaClSrpcArg** inputs,
     NaClSrpcArg** outputs,
     NaClSrpcClosure* done
 ) {
-  PpbGraphics3DRpcServer::PPB_Graphics3DTrusted_GetRingBuffer(
+  UNREFERENCED_PARAMETER(outputs);
+  PpbGraphics3DRpcServer::PPB_Graphics3DTrusted_SetGetBuffer(
       rpc,
       done,
       inputs[0]->u.ival,
-      &(outputs[0]->u.hval),
-      &(outputs[1]->u.ival)
+      inputs[1]->u.ival
   );
 }
 
@@ -2619,8 +2618,8 @@ NaClSrpcHandlerDesc PpbRpcs::srpc_methods[] = {
   { "PPB_Graphics3D_GetError:i:i", PPB_Graphics3D_GetErrorDispatcher },
   { "PPB_Graphics3D_SwapBuffers:ii:i", PPB_Graphics3D_SwapBuffersDispatcher },
   { "PPB_Graphics3DTrusted_CreateRaw:iiI:i", PPB_Graphics3DTrusted_CreateRawDispatcher },
-  { "PPB_Graphics3DTrusted_InitCommandBuffer:ii:i", PPB_Graphics3DTrusted_InitCommandBufferDispatcher },
-  { "PPB_Graphics3DTrusted_GetRingBuffer:i:hi", PPB_Graphics3DTrusted_GetRingBufferDispatcher },
+  { "PPB_Graphics3DTrusted_InitCommandBuffer:i:i", PPB_Graphics3DTrusted_InitCommandBufferDispatcher },
+  { "PPB_Graphics3DTrusted_SetGetBuffer:ii:", PPB_Graphics3DTrusted_SetGetBufferDispatcher },
   { "PPB_Graphics3DTrusted_GetState:i:C", PPB_Graphics3DTrusted_GetStateDispatcher },
   { "PPB_Graphics3DTrusted_Flush:ii:", PPB_Graphics3DTrusted_FlushDispatcher },
   { "PPB_Graphics3DTrusted_FlushSync:ii:C", PPB_Graphics3DTrusted_FlushSyncDispatcher },
diff --git a/ppapi/native_client/src/shared/ppapi_proxy/trusted/srpcgen/ppb_rpc.h b/ppapi/native_client/src/shared/ppapi_proxy/trusted/srpcgen/ppb_rpc.h
index 25feea6..588be46 100644
--- a/ppapi/native_client/src/shared/ppapi_proxy/trusted/srpcgen/ppb_rpc.h
+++ b/ppapi/native_client/src/shared/ppapi_proxy/trusted/srpcgen/ppb_rpc.h
@@ -590,14 +590,12 @@ class PpbGraphics3DRpcServer {
       NaClSrpcRpc* rpc,
       NaClSrpcClosure* done,
       PP_Resource resource_id,
-      int32_t size,
       int32_t* success);
-  static void PPB_Graphics3DTrusted_GetRingBuffer(
+  static void PPB_Graphics3DTrusted_SetGetBuffer(
       NaClSrpcRpc* rpc,
       NaClSrpcClosure* done,
       PP_Resource resource_id,
-      NaClSrpcImcDescType* shm_desc,
-      int32_t* shm_size);
+      int32_t shm_id);
   static void PPB_Graphics3DTrusted_GetState(
       NaClSrpcRpc* rpc,
       NaClSrpcClosure* done,
diff --git a/ppapi/native_client/src/shared/ppapi_proxy/untrusted/srpcgen/ppb_rpc.h b/ppapi/native_client/src/shared/ppapi_proxy/untrusted/srpcgen/ppb_rpc.h
index aa2f7d0..1eee263 100644
--- a/ppapi/native_client/src/shared/ppapi_proxy/untrusted/srpcgen/ppb_rpc.h
+++ b/ppapi/native_client/src/shared/ppapi_proxy/untrusted/srpcgen/ppb_rpc.h
@@ -515,13 +515,11 @@ class PpbGraphics3DRpcClient {
   static NaClSrpcError PPB_Graphics3DTrusted_InitCommandBuffer(
       NaClSrpcChannel* channel,
       PP_Resource resource_id,
-      int32_t size,
       int32_t* success);
-  static NaClSrpcError PPB_Graphics3DTrusted_GetRingBuffer(
+  static NaClSrpcError PPB_Graphics3DTrusted_SetGetBuffer(
       NaClSrpcChannel* channel,
       PP_Resource resource_id,
-      NaClSrpcImcDescType* shm_desc,
-      int32_t* shm_size);
+      int32_t shm_id);
   static NaClSrpcError PPB_Graphics3DTrusted_GetState(
       NaClSrpcChannel* channel,
       PP_Resource resource_id,
diff --git a/ppapi/proxy/ppapi_messages.h b/ppapi/proxy/ppapi_messages.h
index d6f0515..7e277db 100644
--- a/ppapi/proxy/ppapi_messages.h
+++ b/ppapi/proxy/ppapi_messages.h
@@ -781,10 +781,11 @@ IPC_SYNC_MESSAGE_ROUTED2_1(PpapiHostMsg_PPBGraphics3D_Create,
                            PP_Instance /* instance */,
                            std::vector<int32_t> /* attrib_list */,
                            ppapi::HostResource /* result */)
-IPC_SYNC_MESSAGE_ROUTED2_1(PpapiHostMsg_PPBGraphics3D_InitCommandBuffer,
+IPC_SYNC_MESSAGE_ROUTED1_0(PpapiHostMsg_PPBGraphics3D_InitCommandBuffer,
+                           ppapi::HostResource /* context */)
+IPC_SYNC_MESSAGE_ROUTED2_0(PpapiHostMsg_PPBGraphics3D_SetGetBuffer,
                            ppapi::HostResource /* context */,
-                           int32 /* size */,
-                           base::SharedMemoryHandle /* ring_buffer */)
+                           int32 /* transfer_buffer_id */)
 IPC_SYNC_MESSAGE_ROUTED1_1(PpapiHostMsg_PPBGraphics3D_GetState,
                            ppapi::HostResource /* context */,
                            gpu::CommandBuffer::State /* state */)
diff --git a/ppapi/proxy/ppb_graphics_3d_proxy.cc b/ppapi/proxy/ppb_graphics_3d_proxy.cc
index 8203e8d..b5a2dee 100644
--- a/ppapi/proxy/ppb_graphics_3d_proxy.cc
+++ b/ppapi/proxy/ppb_graphics_3d_proxy.cc
@@ -31,13 +31,12 @@ class CommandBuffer : public gpu::CommandBuffer {
   virtual ~CommandBuffer();
 
   // gpu::CommandBuffer implementation:
-  virtual bool Initialize(int32 size);
-  virtual bool Initialize(base::SharedMemory* buffer, int32 size);
-  virtual gpu::Buffer GetRingBuffer();
+  virtual bool Initialize();
   virtual State GetState();
   virtual State GetLastState();
   virtual void Flush(int32 put_offset);
   virtual State FlushSync(int32 put_offset, int32 last_known_get);
+  virtual void SetGetBuffer(int32 transfer_buffer_id);
   virtual void SetGetOffset(int32 get_offset);
   virtual int32 CreateTransferBuffer(size_t size, int32 id_request);
   virtual int32 RegisterTransferBuffer(base::SharedMemory* shared_memory,
@@ -53,9 +52,6 @@ class CommandBuffer : public gpu::CommandBuffer {
   bool Send(IPC::Message* msg);
   void UpdateState(const gpu::CommandBuffer::State& state);
 
-  int32 num_entries_;
-  scoped_ptr<base::SharedMemory> ring_buffer_;
-
   typedef base::hash_map<int32, gpu::Buffer> TransferBufferMap;
   TransferBufferMap transfer_buffers_;
 
@@ -69,8 +65,7 @@ class CommandBuffer : public gpu::CommandBuffer {
 
 CommandBuffer::CommandBuffer(const HostResource& resource,
                              PluginDispatcher* dispatcher)
-    : num_entries_(0),
-      resource_(resource),
+    : resource_(resource),
       dispatcher_(dispatcher) {
 }
 
@@ -84,47 +79,9 @@ CommandBuffer::~CommandBuffer() {
   }
 }
 
-bool CommandBuffer::Initialize(int32 size) {
-  DCHECK(!ring_buffer_.get());
-
-  // Initialize the service. Assuming we are sandboxed, the GPU
-  // process is responsible for duplicating the handle. This might not be true
-  // for NaCl.
-  base::SharedMemoryHandle handle;
-  if (Send(new PpapiHostMsg_PPBGraphics3D_InitCommandBuffer(
-          API_ID_PPB_GRAPHICS_3D, resource_, size, &handle)) &&
-      base::SharedMemory::IsHandleValid(handle)) {
-    ring_buffer_.reset(new base::SharedMemory(handle, false));
-    if (ring_buffer_->Map(size)) {
-      num_entries_ = size / sizeof(gpu::CommandBufferEntry);
-      return true;
-    }
-
-    ring_buffer_.reset();
-  }
-
-  return false;
-}
-
-bool CommandBuffer::Initialize(base::SharedMemory* buffer, int32 size) {
-  // Not implemented in proxy.
-  NOTREACHED();
-  return false;
-}
-
-gpu::Buffer CommandBuffer::GetRingBuffer() {
-  // Return locally cached ring buffer.
-  gpu::Buffer buffer;
-  if (ring_buffer_.get()) {
-    buffer.ptr = ring_buffer_->memory();
-    buffer.size = num_entries_ * sizeof(gpu::CommandBufferEntry);
-    buffer.shared_memory = ring_buffer_.get();
-  } else {
-    buffer.ptr = NULL;
-    buffer.size = 0;
-    buffer.shared_memory = NULL;
-  }
-  return buffer;
+bool CommandBuffer::Initialize() {
+  return Send(new PpapiHostMsg_PPBGraphics3D_InitCommandBuffer(
+      API_ID_PPB_GRAPHICS_3D, resource_));
 }
 
 gpu::CommandBuffer::State CommandBuffer::GetState() {
@@ -175,6 +132,13 @@ gpu::CommandBuffer::State CommandBuffer::FlushSync(int32 put_offset,
   return last_state_;
 }
 
+void CommandBuffer::SetGetBuffer(int32 transfer_buffer_id) {
+  if (last_state_.error == gpu::error::kNoError) {
+    Send(new PpapiHostMsg_PPBGraphics3D_SetGetBuffer(
+        API_ID_PPB_GRAPHICS_3D, resource_, transfer_buffer_id));
+  }
+}
+
 void CommandBuffer::SetGetOffset(int32 get_offset) {
   // Not implemented in proxy.
   NOTREACHED();
@@ -338,17 +302,17 @@ bool Graphics3D::Init() {
     return false;
 
   command_buffer_.reset(new CommandBuffer(host_resource(), dispatcher));
-  if (!command_buffer_->Initialize(kCommandBufferSize))
+  if (!command_buffer_->Initialize())
     return false;
 
   return CreateGLES2Impl(kCommandBufferSize, kTransferBufferSize);
 }
 
-PP_Bool Graphics3D::InitCommandBuffer(int32_t size) {
+PP_Bool Graphics3D::InitCommandBuffer() {
   return PP_FALSE;
 }
 
-PP_Bool Graphics3D::GetRingBuffer(int* shm_handle, uint32_t* shm_size) {
+PP_Bool Graphics3D::SetGetBuffer(int32_t /* transfer_buffer_id */) {
   return PP_FALSE;
 }
 
@@ -449,6 +413,8 @@ bool PPB_Graphics3D_Proxy::OnMessageReceived(const IPC::Message& msg) {
                         OnMsgCreate)
     IPC_MESSAGE_HANDLER(PpapiHostMsg_PPBGraphics3D_InitCommandBuffer,
                         OnMsgInitCommandBuffer)
+    IPC_MESSAGE_HANDLER(PpapiHostMsg_PPBGraphics3D_SetGetBuffer,
+                        OnMsgSetGetBuffer)
     IPC_MESSAGE_HANDLER(PpapiHostMsg_PPBGraphics3D_GetState,
                         OnMsgGetState)
     IPC_MESSAGE_HANDLER(PpapiHostMsg_PPBGraphics3D_Flush,
@@ -488,22 +454,21 @@ void PPB_Graphics3D_Proxy::OnMsgCreate(PP_Instance instance,
 }
 
 void PPB_Graphics3D_Proxy::OnMsgInitCommandBuffer(
-    const HostResource& context,
-    int32 size,
-    base::SharedMemoryHandle* ring_buffer) {
-  *ring_buffer = base::SharedMemory::NULLHandle();
+    const HostResource& context) {
   EnterHostFromHostResource<PPB_Graphics3D_API> enter(context);
   if (enter.failed())
     return;
 
-  if (!enter.object()->InitCommandBuffer(size))
+  if (!enter.object()->InitCommandBuffer())
     return;
+}
 
-  int shm_handle;
-  uint32_t shm_size;
-  if (!enter.object()->GetRingBuffer(&shm_handle, &shm_size))
-    return;
-  *ring_buffer = TransportSHMHandleFromInt(dispatcher(), shm_handle);
+void PPB_Graphics3D_Proxy::OnMsgSetGetBuffer(
+    const HostResource& context,
+    int32 transfer_buffer_id) {
+  EnterHostFromHostResource<PPB_Graphics3D_API> enter(context);
+  if (enter.succeeded())
+    enter.object()->SetGetBuffer(transfer_buffer_id);
 }
 
 void PPB_Graphics3D_Proxy::OnMsgGetState(const HostResource& context,
diff --git a/ppapi/proxy/ppb_graphics_3d_proxy.h b/ppapi/proxy/ppb_graphics_3d_proxy.h
index 472c2a7..bb54b61 100644
--- a/ppapi/proxy/ppb_graphics_3d_proxy.h
+++ b/ppapi/proxy/ppb_graphics_3d_proxy.h
@@ -36,8 +36,8 @@ class Graphics3D : public Resource, public Graphics3DImpl {
   }
 
   // Graphics3DTrusted API. These are not implemented in the proxy.
-  virtual PP_Bool InitCommandBuffer(int32_t size) OVERRIDE;
-  virtual PP_Bool GetRingBuffer(int* shm_handle, uint32_t* shm_size) OVERRIDE;
+  virtual PP_Bool InitCommandBuffer() OVERRIDE;
+  virtual PP_Bool SetGetBuffer(int32_t shm_id) OVERRIDE;
   virtual PP_Graphics3DTrustedState GetState() OVERRIDE;
   virtual PP_Bool Flush(int32_t put_offset) OVERRIDE;
   virtual PP_Graphics3DTrustedState FlushSync(int32_t put_offset) OVERRIDE;
@@ -79,9 +79,9 @@ class PPB_Graphics3D_Proxy : public InterfaceProxy {
   void OnMsgCreate(PP_Instance instance,
                    const std::vector<int32_t>& attribs,
                    HostResource* result);
-  void OnMsgInitCommandBuffer(const HostResource& context,
-                              int32 size,
-                              base::SharedMemoryHandle* ring_buffer);
+  void OnMsgInitCommandBuffer(const HostResource& context);
+  void OnMsgSetGetBuffer(const HostResource& context,
+                         int32 id);
   void OnMsgGetState(const HostResource& context,
                      gpu::CommandBuffer::State* state);
   void OnMsgFlush(const HostResource& context,
diff --git a/ppapi/thunk/ppb_graphics_3d_api.h b/ppapi/thunk/ppb_graphics_3d_api.h
index 73e8178..4e1980a 100644
--- a/ppapi/thunk/ppb_graphics_3d_api.h
+++ b/ppapi/thunk/ppb_graphics_3d_api.h
@@ -25,9 +25,8 @@ class PPAPI_THUNK_EXPORT PPB_Graphics3D_API {
   virtual int32_t SwapBuffers(PP_CompletionCallback callback) = 0;
 
   // Graphics3DTrusted API.
-  virtual PP_Bool InitCommandBuffer(int32_t size) = 0;
-  virtual PP_Bool GetRingBuffer(int* shm_handle,
-                                uint32_t* shm_size) = 0;
+  virtual PP_Bool InitCommandBuffer() = 0;
+  virtual PP_Bool SetGetBuffer(int32_t shm_id) = 0;
   virtual PP_Graphics3DTrustedState GetState() = 0;
   virtual int32_t CreateTransferBuffer(uint32_t size) = 0;
   virtual PP_Bool DestroyTransferBuffer(int32_t id) = 0;
diff --git a/ppapi/thunk/ppb_graphics_3d_trusted_thunk.cc b/ppapi/thunk/ppb_graphics_3d_trusted_thunk.cc
index 5cc9661..bea32ab 100644
--- a/ppapi/thunk/ppb_graphics_3d_trusted_thunk.cc
+++ b/ppapi/thunk/ppb_graphics_3d_trusted_thunk.cc
@@ -30,20 +30,18 @@ PP_Resource CreateRaw(PP_Instance instance,
       instance, share_context, attrib_list);
 }
 
-PP_Bool InitCommandBuffer(PP_Resource context, int32_t size) {
+PP_Bool InitCommandBuffer(PP_Resource context) {
   EnterGraphics3D enter(context, true);
   if (enter.failed())
     return PP_FALSE;
-  return enter.object()->InitCommandBuffer(size);
+  return enter.object()->InitCommandBuffer();
 }
 
-PP_Bool GetRingBuffer(PP_Resource context,
-                      int* shm_handle,
-                      uint32_t* shm_size) {
+PP_Bool SetGetBuffer(PP_Resource context, int32_t transfer_buffer_id) {
   EnterGraphics3D enter(context, true);
   if (enter.failed())
     return PP_FALSE;
-  return enter.object()->GetRingBuffer(shm_handle, shm_size);
+  return enter.object()->SetGetBuffer(transfer_buffer_id);
 }
 
 PP_Graphics3DTrustedState GetState(PP_Resource context) {
@@ -103,7 +101,7 @@ PP_Graphics3DTrustedState FlushSyncFast(PP_Resource context,
 const PPB_Graphics3DTrusted g_ppb_graphics_3d_trusted_thunk = {
   &CreateRaw,
   &InitCommandBuffer,
-  &GetRingBuffer,
+  &SetGetBuffer,
   &GetState,
   &CreateTransferBuffer,
   &DestroyTransferBuffer,