Revert "Revert 113250 - Add CommandBuffer::SetGetBuffer"

This reverts commit bd45bd252aeb8babac62547a5c605fbf64287cd3.

TEST=ran webkit tests in DRT and webgl tests in chrome
BUG=103989

Review URL: http://codereview.chromium.org/8758026

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@113479 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 b894db9..b4e3ec67 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 887ae46..5a6c334 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 PPB_Graphics3D_Shared {
   }
 
   // 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,