Add generated and hand-written passthrough command handlers with stub Doers.

gpu/command_buffer/common/buffer.cc

Index: gpu/command_buffer/common/buffer.cc
diff --git a/gpu/command_buffer/common/buffer.cc b/gpu/command_buffer/common/buffer.cc
index 1bb9523079dd3c094685b9ad306df7697b7526eb..26f78a82251d733a338bf144ac22be044cef4ca7 100644
--- a/gpu/command_buffer/common/buffer.cc
+++ b/gpu/command_buffer/common/buffer.cc
@@ -43,6 +43,22 @@ void* Buffer::GetDataAddress(uint32_t data_offset, uint32_t data_size) const {
   return static_cast<uint8_t*>(memory_) + data_offset;
 }
 
+void* Buffer::GetDataAddressAndSize(uint32_t data_offset,
+                                    uint32_t* data_size) const {
+  base::CheckedNumeric<uint32_t> offset = data_offset;
+  if (!offset.IsValid() || offset.ValueOrDie() > static_cast<uint32_t>(size_))
+    return NULL;

[Zhenyao Mo, 2016/05/25 20:05:49]

I don't really understand why this is necessary (assume you copy the example
from Buffer::GetDataAddress above). There is no numeric operation, so
data_offset should always be valid.

[Geoff Lang, 2016/05/25 20:44:30]

Removed the checks, probably a result of an initial implementation that was
copy-pasted.

+  *data_size = GetRemainingSize(data_offset);
+  return static_cast<uint8_t*>(memory_) + data_offset;
+}
+
+uint32_t Buffer::GetRemainingSize(uint32_t data_offset) const {
+  base::CheckedNumeric<uint32_t> offset = data_offset;
+  if (!offset.IsValid() || offset.ValueOrDie() > static_cast<uint32_t>(size_))
+    return 0;
+  return static_cast<uint32_t>(size_) - data_offset;
+}
+
 base::trace_event::MemoryAllocatorDumpGuid GetBufferGUIDForTracing(
     uint64_t tracing_process_id,
     int32_t buffer_id) {