gpu: Generate mailboxes on client side

Because mailboxes are now just a random number, we don't need to round-trip to
the gpu process to generate them, which lets us get rid of IPCs, layers, etc.

It also means generating a mailbox can't fail any more (even on a lost context),
so, removing some code paths and associated tests.

I'm adding a debug-only verification to ensure the mailboxes are generated from
the crypto-random function (in debug, we burn a byte to compute a mini XOR-check
as a sentinel for "we went through the Generate function"). It's not a secure
check, but should hit incorrect/unsafe usage.

BUG=None

Review URL: https://codereview.chromium.org/165393003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@251570 0039d316-1c4b-4281-b951-d872f2087c98

19 files changed, 119 insertions, 117 deletions

diff --git a/gpu/command_buffer/build_gles2_cmd_buffer.py b/gpu/command_buffer/build_gles2_cmd_buffer.py
index 23dacf1..8e779e3 100755
--- a/gpu/command_buffer/build_gles2_cmd_buffer.py
+++ b/gpu/command_buffer/build_gles2_cmd_buffer.py
@@ -1325,10 +1325,12 @@ _FUNCTION_INFO = {
   },
   'ConsumeTextureCHROMIUM': {
     'decoder_func': 'DoConsumeTextureCHROMIUM',
+    'impl_func': False,
     'type': 'PUT',
     'data_type': 'GLbyte',
     'count': 64,  # GL_MAILBOX_SIZE_CHROMIUM
     'unit_test': False,
+    'client_test': False,
     'extension': True,
     'chromium': True,
     'trace_level': 1,
@@ -1908,10 +1910,12 @@ _FUNCTION_INFO = {
   },
   'ProduceTextureCHROMIUM': {
     'decoder_func': 'DoProduceTextureCHROMIUM',
+    'impl_func': False,
     'type': 'PUT',
     'data_type': 'GLbyte',
     'count': 64,  # GL_MAILBOX_SIZE_CHROMIUM
     'unit_test': False,
+    'client_test': False,
     'extension': True,
     'chromium': True,
     'trace_level': 1,
@@ -4790,6 +4794,9 @@ TEST_F(%(test_name)s, %(name)sInvalidArgs%(arg_index)d_%(value_index)d) {
 
   def WriteGLES2Implementation(self, func, file):
     """Overrriden from TypeHandler."""
+    impl_func = func.GetInfo('impl_func')
+    if (impl_func != None and impl_func != True):
+      return;
     file.Write("%s GLES2Implementation::%s(%s) {\n" %
                (func.return_type, func.original_name,
                 func.MakeTypedOriginalArgString("")))
@@ -4810,6 +4817,9 @@ TEST_F(%(test_name)s, %(name)sInvalidArgs%(arg_index)d_%(value_index)d) {
 
   def WriteGLES2ImplementationUnitTest(self, func, file):
     """Writes the GLES2 Implemention unit test."""
+    client_test = func.GetInfo('client_test')
+    if (client_test != None and client_test != True):
+      return;
     code = """
 TEST_F(GLES2ImplementationTest, %(name)s) {
   %(type)s data[%(count)d] = {0};
diff --git a/gpu/command_buffer/client/client_test_helper.h b/gpu/command_buffer/client/client_test_helper.h
index c6d6e02..88c37e8 100644
--- a/gpu/command_buffer/client/client_test_helper.h
+++ b/gpu/command_buffer/client/client_test_helper.h
@@ -94,8 +94,6 @@ class MockClientGpuControl : public GpuControl {
                                      unsigned internalformat,
                                      int32* id));
   MOCK_METHOD1(DestroyGpuMemoryBuffer, void(int32 id));
-  MOCK_METHOD2(GenerateMailboxNames, bool(unsigned num,
-                                          std::vector<gpu::Mailbox>* names));
   MOCK_METHOD0(InsertSyncPoint, uint32());
   MOCK_METHOD2(SignalSyncPoint, void(uint32 id,
                                      const base::Closure& callback));
diff --git a/gpu/command_buffer/client/gles2_implementation.cc b/gpu/command_buffer/client/gles2_implementation.cc
index b99b332..9275a49 100644
--- a/gpu/command_buffer/client/gles2_implementation.cc
+++ b/gpu/command_buffer/client/gles2_implementation.cc
@@ -3472,12 +3472,34 @@ void GLES2Implementation::GenMailboxCHROMIUM(
       << static_cast<const void*>(mailbox) << ")");
   TRACE_EVENT0("gpu", "GLES2::GenMailboxCHROMIUM");
 
-  std::vector<gpu::Mailbox> names;
-  if (!gpu_control_->GenerateMailboxNames(1, &names)) {
-    SetGLError(GL_OUT_OF_MEMORY, "glGenMailboxCHROMIUM", "Generate failed.");
-    return;
-  }
-  memcpy(mailbox, names[0].name, GL_MAILBOX_SIZE_CHROMIUM);
+  gpu::Mailbox result = gpu::Mailbox::Generate();
+  memcpy(mailbox, result.name, sizeof(result.name));
+}
+
+void GLES2Implementation::ProduceTextureCHROMIUM(GLenum target,
+                                                 const GLbyte* data) {
+  GPU_CLIENT_SINGLE_THREAD_CHECK();
+  GPU_CLIENT_LOG("[" << GetLogPrefix() << "] glProduceTextureCHROMIUM("
+                     << static_cast<const void*>(data) << ")");
+  const Mailbox& mailbox = *reinterpret_cast<const Mailbox*>(data);
+  DCHECK(mailbox.Verify()) << "ProduceTextureCHROMIUM was passed a "
+                              "mailbox that was not generated by "
+                              "GenMailboxCHROMIUM.";
+  helper_->ProduceTextureCHROMIUMImmediate(target, data);
+  CheckGLError();
+}
+
+void GLES2Implementation::ConsumeTextureCHROMIUM(GLenum target,
+                                                 const GLbyte* data) {
+  GPU_CLIENT_SINGLE_THREAD_CHECK();
+  GPU_CLIENT_LOG("[" << GetLogPrefix() << "] glConsumeTextureCHROMIUM("
+                     << static_cast<const void*>(data) << ")");
+  const Mailbox& mailbox = *reinterpret_cast<const Mailbox*>(data);
+  DCHECK(mailbox.Verify()) << "ConsumeTextureCHROMIUM was passed a "
+                              "mailbox that was not generated by "
+                              "GenMailboxCHROMIUM.";
+  helper_->ConsumeTextureCHROMIUMImmediate(target, data);
+  CheckGLError();
 }
 
 void GLES2Implementation::PushGroupMarkerEXT(
diff --git a/gpu/command_buffer/client/gles2_implementation_impl_autogen.h b/gpu/command_buffer/client/gles2_implementation_impl_autogen.h
index 9dba99f..11c1df0 100644
--- a/gpu/command_buffer/client/gles2_implementation_impl_autogen.h
+++ b/gpu/command_buffer/client/gles2_implementation_impl_autogen.h
@@ -1678,24 +1678,6 @@ void GLES2Implementation::CopyTextureCHROMIUM(
   CheckGLError();
 }
 
-void GLES2Implementation::ProduceTextureCHROMIUM(
-    GLenum target, const GLbyte* mailbox) {
-  GPU_CLIENT_SINGLE_THREAD_CHECK();
-  GPU_CLIENT_LOG("[" << GetLogPrefix() << "] glProduceTextureCHROMIUM(" << GLES2Util::GetStringTextureBindTarget(target) << ", " << static_cast<const void*>(mailbox) << ")");  // NOLINT
-  GPU_CLIENT_LOG("values: " << mailbox[0] << ", " << mailbox[1] << ", " << mailbox[2] << ", " << mailbox[3] << ", " << mailbox[4] << ", " << mailbox[5] << ", " << mailbox[6] << ", " << mailbox[7] << ", " << mailbox[8] << ", " << mailbox[9] << ", " << mailbox[10] << ", " << mailbox[11] << ", " << mailbox[12] << ", " << mailbox[13] << ", " << mailbox[14] << ", " << mailbox[15] << ", " << mailbox[16] << ", " << mailbox[17] << ", " << mailbox[18] << ", " << mailbox[19] << ", " << mailbox[20] << ", " << mailbox[21] << ", " << mailbox[22] << ", " << mailbox[23] << ", " << mailbox[24] << ", " << mailbox[25] << ", " << mailbox[26] << ", " << mailbox[27] << ", " << mailbox[28] << ", " << mailbox[29] << ", " << mailbox[30] << ", " << mailbox[31] << ", " << mailbox[32] << ", " << mailbox[33] << ", " << mailbox[34] << ", " << mailbox[35] << ", " << mailbox[36] << ", " << mailbox[37] << ", " << mailbox[38] << ", " << mailbox[39] << ", " << mailbox[40] << ", " << mailbox[41] << ", " << mailbox[42] << ", " << mailbox[43] << ", " << mailbox[44] << ", " << mailbox[45] << ", " << mailbox[46] << ", " << mailbox[47] << ", " << mailbox[48] << ", " << mailbox[49] << ", " << mailbox[50] << ", " << mailbox[51] << ", " << mailbox[52] << ", " << mailbox[53] << ", " << mailbox[54] << ", " << mailbox[55] << ", " << mailbox[56] << ", " << mailbox[57] << ", " << mailbox[58] << ", " << mailbox[59] << ", " << mailbox[60] << ", " << mailbox[61] << ", " << mailbox[62] << ", " << mailbox[63]);  // NOLINT
-  helper_->ProduceTextureCHROMIUMImmediate(target, mailbox);
-  CheckGLError();
-}
-
-void GLES2Implementation::ConsumeTextureCHROMIUM(
-    GLenum target, const GLbyte* mailbox) {
-  GPU_CLIENT_SINGLE_THREAD_CHECK();
-  GPU_CLIENT_LOG("[" << GetLogPrefix() << "] glConsumeTextureCHROMIUM(" << GLES2Util::GetStringTextureBindTarget(target) << ", " << static_cast<const void*>(mailbox) << ")");  // NOLINT
-  GPU_CLIENT_LOG("values: " << mailbox[0] << ", " << mailbox[1] << ", " << mailbox[2] << ", " << mailbox[3] << ", " << mailbox[4] << ", " << mailbox[5] << ", " << mailbox[6] << ", " << mailbox[7] << ", " << mailbox[8] << ", " << mailbox[9] << ", " << mailbox[10] << ", " << mailbox[11] << ", " << mailbox[12] << ", " << mailbox[13] << ", " << mailbox[14] << ", " << mailbox[15] << ", " << mailbox[16] << ", " << mailbox[17] << ", " << mailbox[18] << ", " << mailbox[19] << ", " << mailbox[20] << ", " << mailbox[21] << ", " << mailbox[22] << ", " << mailbox[23] << ", " << mailbox[24] << ", " << mailbox[25] << ", " << mailbox[26] << ", " << mailbox[27] << ", " << mailbox[28] << ", " << mailbox[29] << ", " << mailbox[30] << ", " << mailbox[31] << ", " << mailbox[32] << ", " << mailbox[33] << ", " << mailbox[34] << ", " << mailbox[35] << ", " << mailbox[36] << ", " << mailbox[37] << ", " << mailbox[38] << ", " << mailbox[39] << ", " << mailbox[40] << ", " << mailbox[41] << ", " << mailbox[42] << ", " << mailbox[43] << ", " << mailbox[44] << ", " << mailbox[45] << ", " << mailbox[46] << ", " << mailbox[47] << ", " << mailbox[48] << ", " << mailbox[49] << ", " << mailbox[50] << ", " << mailbox[51] << ", " << mailbox[52] << ", " << mailbox[53] << ", " << mailbox[54] << ", " << mailbox[55] << ", " << mailbox[56] << ", " << mailbox[57] << ", " << mailbox[58] << ", " << mailbox[59] << ", " << mailbox[60] << ", " << mailbox[61] << ", " << mailbox[62] << ", " << mailbox[63]);  // NOLINT
-  helper_->ConsumeTextureCHROMIUMImmediate(target, mailbox);
-  CheckGLError();
-}
-
 void GLES2Implementation::BindTexImage2DCHROMIUM(
     GLenum target, GLint imageId) {
   GPU_CLIENT_SINGLE_THREAD_CHECK();
diff --git a/gpu/command_buffer/client/gles2_implementation_unittest.cc b/gpu/command_buffer/client/gles2_implementation_unittest.cc
index 6103309..b6803ba 100644
--- a/gpu/command_buffer/client/gles2_implementation_unittest.cc
+++ b/gpu/command_buffer/client/gles2_implementation_unittest.cc
@@ -2845,6 +2845,31 @@ TEST_F(GLES2ImplementationTest, Enable) {
   EXPECT_TRUE(NoCommandsWritten());
 }
 
+TEST_F(GLES2ImplementationTest, ConsumeTextureCHROMIUM) {
+  struct Cmds {
+    cmds::ConsumeTextureCHROMIUMImmediate cmd;
+    GLbyte data[64];
+  };
+
+  Mailbox mailbox = Mailbox::Generate();
+  Cmds expected;
+  expected.cmd.Init(GL_TEXTURE_2D, mailbox.name);
+  gl_->ConsumeTextureCHROMIUM(GL_TEXTURE_2D, mailbox.name);
+  EXPECT_EQ(0, memcmp(&expected, commands_, sizeof(expected)));
+}
+
+TEST_F(GLES2ImplementationTest, ProduceTextureCHROMIUM) {
+  struct Cmds {
+    cmds::ProduceTextureCHROMIUMImmediate cmd;
+    GLbyte data[64];
+  };
+
+  Mailbox mailbox = Mailbox::Generate();
+  Cmds expected;
+  expected.cmd.Init(GL_TEXTURE_2D, mailbox.name);
+  gl_->ProduceTextureCHROMIUM(GL_TEXTURE_2D, mailbox.name);
+  EXPECT_EQ(0, memcmp(&expected, commands_, sizeof(expected)));
+}
 
 #include "gpu/command_buffer/client/gles2_implementation_unittest_autogen.h"
 
diff --git a/gpu/command_buffer/client/gles2_implementation_unittest_autogen.h b/gpu/command_buffer/client/gles2_implementation_unittest_autogen.h
index 6cefd1d..172b1b3 100644
--- a/gpu/command_buffer/client/gles2_implementation_unittest_autogen.h
+++ b/gpu/command_buffer/client/gles2_implementation_unittest_autogen.h
@@ -1738,38 +1738,6 @@ TEST_F(GLES2ImplementationTest, VertexAttribDivisorANGLE) {
   EXPECT_EQ(0, memcmp(&expected, commands_, sizeof(expected)));
 }
 // TODO: Implement unit test for GenMailboxCHROMIUM
-
-TEST_F(GLES2ImplementationTest, ProduceTextureCHROMIUM) {
-  GLbyte data[64] = {0};
-  struct Cmds {
-    cmds::ProduceTextureCHROMIUMImmediate cmd;
-    GLbyte data[64];
-  };
-
-  for (int jj = 0; jj < 64; ++jj) {
-    data[jj] = static_cast<GLbyte>(jj);
-  }
-  Cmds expected;
-  expected.cmd.Init(GL_TEXTURE_2D, &data[0]);
-  gl_->ProduceTextureCHROMIUM(GL_TEXTURE_2D, &data[0]);
-  EXPECT_EQ(0, memcmp(&expected, commands_, sizeof(expected)));
-}
-
-TEST_F(GLES2ImplementationTest, ConsumeTextureCHROMIUM) {
-  GLbyte data[64] = {0};
-  struct Cmds {
-    cmds::ConsumeTextureCHROMIUMImmediate cmd;
-    GLbyte data[64];
-  };
-
-  for (int jj = 0; jj < 64; ++jj) {
-    data[jj] = static_cast<GLbyte>(jj);
-  }
-  Cmds expected;
-  expected.cmd.Init(GL_TEXTURE_2D, &data[0]);
-  gl_->ConsumeTextureCHROMIUM(GL_TEXTURE_2D, &data[0]);
-  EXPECT_EQ(0, memcmp(&expected, commands_, sizeof(expected)));
-}
 // TODO: Implement unit test for BindUniformLocationCHROMIUM
 
 TEST_F(GLES2ImplementationTest, BindTexImage2DCHROMIUM) {
diff --git a/gpu/command_buffer/common/gpu_control.h b/gpu/command_buffer/common/gpu_control.h
index 448ab1d..e15d5e6 100644
--- a/gpu/command_buffer/common/gpu_control.h
+++ b/gpu/command_buffer/common/gpu_control.h
@@ -39,11 +39,6 @@ class GPU_EXPORT GpuControl {
   // Destroy a gpu memory buffer. The ID must be positive.
   virtual void DestroyGpuMemoryBuffer(int32 id) = 0;
 
-  // Generates n unique mailbox names that can be used with
-  // GL_texture_mailbox_CHROMIUM.
-  virtual bool GenerateMailboxNames(unsigned num,
-                                    std::vector<gpu::Mailbox>* names) = 0;
-
   // Inserts a sync point, returning its ID. Sync point IDs are global and can
   // be used for cross-context synchronization.
   virtual uint32 InsertSyncPoint() = 0;
diff --git a/gpu/command_buffer/common/mailbox.cc b/gpu/command_buffer/common/mailbox.cc
index 8d8393f..21602ab 100644
--- a/gpu/command_buffer/common/mailbox.cc
+++ b/gpu/command_buffer/common/mailbox.cc
@@ -7,6 +7,7 @@
 #include <string.h>
 
 #include "base/logging.h"
+#include "base/rand_util.h"
 
 namespace gpu {
 
@@ -31,4 +32,28 @@ void Mailbox::SetName(const int8* n) {
   memcpy(name, n, sizeof(name));
 }
 
+Mailbox Mailbox::Generate() {
+  Mailbox result;
+  // Generates cryptographically-secure bytes.
+  base::RandBytes(result.name, sizeof(result.name));
+#if !defined(NDEBUG)
+  int8 value = 1;
+  for (size_t i = 1; i < sizeof(result.name); ++i)
+    value ^= result.name[i];
+  result.name[0] = value;
+#endif
+  return result;
+}
+
+bool Mailbox::Verify() const {
+#if !defined(NDEBUG)
+  int8 value = 1;
+  for (size_t i = 0; i < sizeof(name); ++i)
+    value ^= name[i];
+  return value == 0;
+#else
+  return true;
+#endif
+}
+
 }  // namespace gpu
diff --git a/gpu/command_buffer/common/mailbox.h b/gpu/command_buffer/common/mailbox.h
index 08a970f..06b4b59 100644
--- a/gpu/command_buffer/common/mailbox.h
+++ b/gpu/command_buffer/common/mailbox.h
@@ -22,6 +22,15 @@ struct GPU_EXPORT Mailbox {
   bool IsZero() const;
   void SetZero();
   void SetName(const int8* name);
+
+  // Generate a unique unguessable mailbox name.
+  static Mailbox Generate();
+
+  // Verify that the mailbox was created through Mailbox::Generate. This only
+  // works in Debug (always returns true in Release). This is not a secure
+  // check, only to catch bugs where clients forgot to call Mailbox::Generate.
+  bool Verify() const;
+
   int8 name[GL_MAILBOX_SIZE_CHROMIUM];
   bool operator<(const Mailbox& other) const {
     return memcmp(this, &other, sizeof other) < 0;
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder.cc b/gpu/command_buffer/service/gles2_cmd_decoder.cc
index 414ecc6..ffa66ed 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -10005,10 +10005,15 @@ error::Error GLES2DecoderImpl::HandleGenMailboxCHROMIUM(
 }
 
 void GLES2DecoderImpl::DoProduceTextureCHROMIUM(GLenum target,
-                                                const GLbyte* mailbox) {
+                                                const GLbyte* data) {
   TRACE_EVENT2("gpu", "GLES2DecoderImpl::DoProduceTextureCHROMIUM",
       "context", logger_.GetLogPrefix(),
-      "mailbox[0]", static_cast<unsigned char>(mailbox[0]));
+      "mailbox[0]", static_cast<unsigned char>(data[0]));
+
+  const Mailbox& mailbox = *reinterpret_cast<const Mailbox*>(data);
+  DLOG_IF(ERROR, !mailbox.Verify()) << "ProduceTextureCHROMIUM was passed a "
+                                       "mailbox that was not generated by "
+                                       "GenMailboxCHROMIUM.";
 
   TextureRef* texture_ref = texture_manager()->GetTextureInfoForTarget(
       &state_, target);
@@ -10027,17 +10032,18 @@ void GLES2DecoderImpl::DoProduceTextureCHROMIUM(GLenum target,
     return;
   }
 
-  group_->mailbox_manager()->ProduceTexture(
-      target,
-      *reinterpret_cast<const Mailbox*>(mailbox),
-      produced);
+  group_->mailbox_manager()->ProduceTexture(target, mailbox, produced);
 }
 
 void GLES2DecoderImpl::DoConsumeTextureCHROMIUM(GLenum target,
-                                                const GLbyte* mailbox) {
+                                                const GLbyte* data) {
   TRACE_EVENT2("gpu", "GLES2DecoderImpl::DoConsumeTextureCHROMIUM",
       "context", logger_.GetLogPrefix(),
-      "mailbox[0]", static_cast<unsigned char>(mailbox[0]));
+      "mailbox[0]", static_cast<unsigned char>(data[0]));
+  const Mailbox& mailbox = *reinterpret_cast<const Mailbox*>(data);
+  DLOG_IF(ERROR, !mailbox.Verify()) << "ConsumeTextureCHROMIUM was passed a "
+                                       "mailbox that was not generated by "
+                                       "GenMailboxCHROMIUM.";
 
   scoped_refptr<TextureRef> texture_ref =
       texture_manager()->GetTextureInfoForTargetUnlessDefault(&state_, target);
@@ -10054,10 +10060,7 @@ void GLES2DecoderImpl::DoConsumeTextureCHROMIUM(GLenum target,
         "glConsumeTextureCHROMIUM", "unknown texture for target");
     return;
   }
-  Texture* texture =
-      group_->mailbox_manager()->ConsumeTexture(
-      target,
-      *reinterpret_cast<const Mailbox*>(mailbox));
+  Texture* texture = group_->mailbox_manager()->ConsumeTexture(target, mailbox);
   if (!texture) {
     LOCAL_SET_GL_ERROR(
         GL_INVALID_OPERATION,
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder_unittest.cc b/gpu/command_buffer/service/gles2_cmd_decoder_unittest.cc
index 4d1c77e..e7187d0 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder_unittest.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder_unittest.cc
@@ -7071,8 +7071,7 @@ TEST_F(GLES2DecoderTest, BeginEndQueryEXTGetErrorQueryCHROMIUM) {
 }
 
 TEST_F(GLES2DecoderTest, ProduceAndConsumeTextureCHROMIUM) {
-  Mailbox mailbox;
-  group().mailbox_manager()->GenerateMailbox(&mailbox);
+  Mailbox mailbox = Mailbox::Generate();
 
   memcpy(shared_memory_address_, mailbox.name, sizeof(mailbox.name));
 
diff --git a/gpu/command_buffer/service/gpu_control_service.cc b/gpu/command_buffer/service/gpu_control_service.cc
index 9a198e6..893b872 100644
--- a/gpu/command_buffer/service/gpu_control_service.cc
+++ b/gpu/command_buffer/service/gpu_control_service.cc
@@ -123,13 +123,4 @@ bool GpuControlService::RegisterGpuMemoryBuffer(
                                                              internalformat);
 }
 
-bool GpuControlService::GenerateMailboxNames(
-    unsigned num, std::vector<gpu::Mailbox>* names) {
-  DCHECK(names->empty());
-  names->resize(num);
-  for (unsigned i = 0; i < num; ++i)
-    mailbox_manager_->GenerateMailbox(&(*names)[i]);
-  return true;
-}
-
 }  // namespace gpu
diff --git a/gpu/command_buffer/service/gpu_control_service.h b/gpu/command_buffer/service/gpu_control_service.h
index 9e36f15..74fd4d5 100644
--- a/gpu/command_buffer/service/gpu_control_service.h
+++ b/gpu/command_buffer/service/gpu_control_service.h
@@ -38,8 +38,6 @@ class GPU_EXPORT GpuControlService : public GpuControl {
       unsigned internalformat,
       int32* id) OVERRIDE;
   virtual void DestroyGpuMemoryBuffer(int32 id) OVERRIDE;
-  virtual bool GenerateMailboxNames(unsigned num,
-                                    std::vector<gpu::Mailbox>* names) OVERRIDE;
   virtual uint32 InsertSyncPoint() OVERRIDE;
   virtual void SignalSyncPoint(uint32 sync_point,
                                const base::Closure& callback) OVERRIDE;
diff --git a/gpu/command_buffer/service/in_process_command_buffer.cc b/gpu/command_buffer/service/in_process_command_buffer.cc
index ba469ee..5bc7ded 100644
--- a/gpu/command_buffer/service/in_process_command_buffer.cc
+++ b/gpu/command_buffer/service/in_process_command_buffer.cc
@@ -551,13 +551,6 @@ void InProcessCommandBuffer::DestroyGpuMemoryBuffer(int32 id) {
   QueueTask(task);
 }
 
-bool InProcessCommandBuffer::GenerateMailboxNames(
-    unsigned num, std::vector<gpu::Mailbox>* names) {
-  CheckSequencedThread();
-  base::AutoLock lock(command_buffer_lock_);
-  return gpu_control_->GenerateMailboxNames(num, names);
-}
-
 uint32 InProcessCommandBuffer::InsertSyncPoint() {
   return 0;
 }
diff --git a/gpu/command_buffer/service/in_process_command_buffer.h b/gpu/command_buffer/service/in_process_command_buffer.h
index e469f78..199a294 100644
--- a/gpu/command_buffer/service/in_process_command_buffer.h
+++ b/gpu/command_buffer/service/in_process_command_buffer.h
@@ -104,8 +104,6 @@ class GPU_EXPORT InProcessCommandBuffer : public CommandBuffer,
       unsigned internalformat,
       int32* id) OVERRIDE;
   virtual void DestroyGpuMemoryBuffer(int32 id) OVERRIDE;
-  virtual bool GenerateMailboxNames(unsigned num,
-                                    std::vector<gpu::Mailbox>* names) OVERRIDE;
   virtual uint32 InsertSyncPoint() OVERRIDE;
   virtual void SignalSyncPoint(uint32 sync_point,
                                const base::Closure& callback) OVERRIDE;
diff --git a/gpu/command_buffer/service/mailbox_manager.cc b/gpu/command_buffer/service/mailbox_manager.cc
index e2fb86f..c337b48 100644
--- a/gpu/command_buffer/service/mailbox_manager.cc
+++ b/gpu/command_buffer/service/mailbox_manager.cc
@@ -21,10 +21,6 @@ MailboxManager::~MailboxManager() {
   DCHECK(textures_to_mailboxes_.empty());
 }
 
-void MailboxManager::GenerateMailbox(Mailbox* mailbox) {
-  crypto::RandBytes(mailbox->name, sizeof(mailbox->name));
-}
-
 Texture* MailboxManager::ConsumeTexture(unsigned target,
                                         const Mailbox& mailbox) {
   MailboxToTextureMap::iterator it =
diff --git a/gpu/command_buffer/service/mailbox_manager.h b/gpu/command_buffer/service/mailbox_manager.h
index 453863b..a231979 100644
--- a/gpu/command_buffer/service/mailbox_manager.h
+++ b/gpu/command_buffer/service/mailbox_manager.h
@@ -27,9 +27,6 @@ class GPU_EXPORT MailboxManager : public base::RefCounted<MailboxManager> {
  public:
   MailboxManager();
 
-  // Generate a unique unguessable mailbox name.
-  void GenerateMailbox(Mailbox* mailbox);
-
   // Look up the texture definition from the named mailbox.
   Texture* ConsumeTexture(unsigned target, const Mailbox& mailbox);
 
diff --git a/gpu/command_buffer/service/mailbox_manager_unittest.cc b/gpu/command_buffer/service/mailbox_manager_unittest.cc
index 9e1ff6b..f7a4155 100644
--- a/gpu/command_buffer/service/mailbox_manager_unittest.cc
+++ b/gpu/command_buffer/service/mailbox_manager_unittest.cc
@@ -34,8 +34,7 @@ class MailboxManagerTest : public testing::Test {
 TEST_F(MailboxManagerTest, Basic) {
   Texture* texture = CreateTexture();
 
-  Mailbox name;
-  manager_->GenerateMailbox(&name);
+  Mailbox name = Mailbox::Generate();
   manager_->ProduceTexture(0, name, texture);
   EXPECT_EQ(texture, manager_->ConsumeTexture(0, name));
 
@@ -54,8 +53,7 @@ TEST_F(MailboxManagerTest, Basic) {
 TEST_F(MailboxManagerTest, ProduceMultipleMailbox) {
   Texture* texture = CreateTexture();
 
-  Mailbox name1;
-  manager_->GenerateMailbox(&name1);
+  Mailbox name1 = Mailbox::Generate();
 
   manager_->ProduceTexture(0, name1, texture);
   EXPECT_EQ(texture, manager_->ConsumeTexture(0, name1));
@@ -65,8 +63,7 @@ TEST_F(MailboxManagerTest, ProduceMultipleMailbox) {
   EXPECT_EQ(texture, manager_->ConsumeTexture(0, name1));
 
   // Can produce again, with a different mailbox.
-  Mailbox name2;
-  manager_->GenerateMailbox(&name2);
+  Mailbox name2 = Mailbox::Generate();
   manager_->ProduceTexture(0, name2, texture);
 
   // Still available under all mailboxes.
@@ -85,8 +82,7 @@ TEST_F(MailboxManagerTest, ProduceMultipleTexture) {
   Texture* texture1 = CreateTexture();
   Texture* texture2 = CreateTexture();
 
-  Mailbox name;
-  manager_->GenerateMailbox(&name);
+  Mailbox name = Mailbox::Generate();
 
   manager_->ProduceTexture(0, name, texture1);
   EXPECT_EQ(texture1, manager_->ConsumeTexture(0, name));
@@ -107,10 +103,8 @@ TEST_F(MailboxManagerTest, ProduceMultipleTexture) {
 TEST_F(MailboxManagerTest, ProduceMultipleTextureMailbox) {
   Texture* texture1 = CreateTexture();
   Texture* texture2 = CreateTexture();
-  Mailbox name1;
-  manager_->GenerateMailbox(&name1);
-  Mailbox name2;
-  manager_->GenerateMailbox(&name2);
+  Mailbox name1 = Mailbox::Generate();
+  Mailbox name2 = Mailbox::Generate();
 
   // Put texture1 on name1 and name2.
   manager_->ProduceTexture(0, name1, texture1);
diff --git a/gpu/command_buffer/tests/gl_texture_mailbox_unittest.cc b/gpu/command_buffer/tests/gl_texture_mailbox_unittest.cc
index 50a3bbc..ba3324d 100644
--- a/gpu/command_buffer/tests/gl_texture_mailbox_unittest.cc
+++ b/gpu/command_buffer/tests/gl_texture_mailbox_unittest.cc
@@ -130,7 +130,6 @@ TEST_F(GLTextureMailboxTest, ConsumeTextureValidatesKey) {
 
   GLbyte invalid_mailbox[GL_MAILBOX_SIZE_CHROMIUM];
   glGenMailboxCHROMIUM(invalid_mailbox);
-  ++invalid_mailbox[GL_MAILBOX_SIZE_CHROMIUM - 1];
 
   EXPECT_EQ(static_cast<GLenum>(GL_NO_ERROR), glGetError());
   glConsumeTextureCHROMIUM(GL_TEXTURE_2D, invalid_mailbox);