Update from https://crrev.com/314320

gpu/command_buffer/client/gles2_implementation.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // A class to emulate GLES2 over command buffers.
 
 #include "gpu/command_buffer/client/gles2_implementation.h"
 
 #include <GLES2/gl2ext.h>
 #include <GLES2/gl2extchromium.h>
 #include <GLES3/gl3.h>
 #include <algorithm>
 #include <limits>
 #include <map>
 #include <queue>
 #include <set>
 #include <sstream>
 #include <string>
 #include "base/bind.h"
+#include "base/compiler_specific.h"
 #include "base/numerics/safe_math.h"
 #include "gpu/command_buffer/client/buffer_tracker.h"
 #include "gpu/command_buffer/client/gpu_control.h"
 #include "gpu/command_buffer/client/program_info_manager.h"
 #include "gpu/command_buffer/client/query_tracker.h"
 #include "gpu/command_buffer/client/transfer_buffer.h"
 #include "gpu/command_buffer/client/vertex_array_object_manager.h"
 #include "gpu/command_buffer/common/gles2_cmd_utils.h"
 #include "gpu/command_buffer/common/trace_event.h"
 
@@ skipping 1202 matching lines @@
   vertex_array_object_manager_->SetAttribDivisor(index, divisor);
   helper_->VertexAttribDivisorANGLE(index, divisor);
   CheckGLError();
 }
 
 void GLES2Implementation::BufferDataHelper(
     GLenum target, GLsizeiptr size, const void* data, GLenum usage) {
   if (!ValidateSize("glBufferData", size))
     return;
 
+#if defined(MEMORY_SANITIZER) && !defined(OS_NACL)
+  // Do not upload uninitialized data. Even if it's not a bug, it can cause a
+  // bogus MSan report during a readback later. This is because MSan doesn't
+  // understand shared memory and would assume we were reading back the same
+  // unintialized data.
+  if (data) __msan_check_mem_is_initialized(data, size);
+#endif
+
   GLuint buffer_id;
   if (GetBoundPixelTransferBuffer(target, "glBufferData", &buffer_id)) {
     if (!buffer_id) {
       return;
     }
 
     BufferTracker::Buffer* buffer = buffer_tracker_->GetBuffer(buffer_id);
     if (buffer)
       RemoveTransferBuffer(buffer);
 
@@ skipping 3121 matching lines @@
   return false;
 }
 
 // Include the auto-generated part of this file. We split this because it means
 // we can easily edit the non-auto generated parts right here in this file
 // instead of having to edit some template or the code generator.
 #include "gpu/command_buffer/client/gles2_implementation_impl_autogen.h"
 
 }  // namespace gles2
 }  // namespace gpu