Add offset support to BitstreamBuffer.

content/common/gpu/media/vaapi_video_encode_accelerator.cc

Index: content/common/gpu/media/vaapi_video_encode_accelerator.cc
diff --git a/content/common/gpu/media/vaapi_video_encode_accelerator.cc b/content/common/gpu/media/vaapi_video_encode_accelerator.cc
index 049cd7a5547ef7c062bed0eb898b3f6187dee502..4e2a06e75f1eb3607886703ed4b0ffcaf2037de0 100644
--- a/content/common/gpu/media/vaapi_video_encode_accelerator.cc
+++ b/content/common/gpu/media/vaapi_video_encode_accelerator.cc
@@ -13,6 +13,7 @@
 #include "base/metrics/histogram.h"
 #include "base/numerics/safe_conversions.h"
 #include "content/common/gpu/media/h264_dpb.h"
+#include "content/common/gpu/media/shared_memory_region.h"
 #include "media/base/bind_to_current_loop.h"
 #include "third_party/libva/va/va_enc_h264.h"
 
@@ -100,13 +101,10 @@ struct VaapiVideoEncodeAccelerator::InputFrameRef {
 };
 
 struct VaapiVideoEncodeAccelerator::BitstreamBufferRef {
-  BitstreamBufferRef(int32_t id,
-                     scoped_ptr<base::SharedMemory> shm,
-                     size_t size)
-      : id(id), shm(std::move(shm)), size(size) {}
+  BitstreamBufferRef(int32_t id, scoped_ptr<SharedMemoryRegion> shm)
+      : id(id), shm(std::move(shm)) {}
   const int32_t id;
-  const scoped_ptr<base::SharedMemory> shm;
-  const size_t size;
+  const scoped_ptr<SharedMemoryRegion> shm;
 };
 
 media::VideoEncodeAccelerator::SupportedProfiles
@@ -546,11 +544,8 @@ void VaapiVideoEncodeAccelerator::TryToReturnBitstreamBuffer() {
 
   size_t data_size = 0;
   if (!vaapi_wrapper_->DownloadAndDestroyCodedBuffer(
-          encode_job->coded_buffer,
-          encode_job->input_surface->id(),
-          target_data,
-          buffer->size,
-          &data_size)) {
+          encode_job->coded_buffer, encode_job->input_surface->id(),
+          target_data, buffer->shm->size(), &data_size)) {
     NOTIFY_ERROR(kPlatformFailureError, "Failed downloading coded buffer");
     return;
   }
@@ -669,15 +664,14 @@ void VaapiVideoEncodeAccelerator::UseOutputBitstreamBuffer(
     return;
   }
 
-  scoped_ptr<base::SharedMemory> shm(
-      new base::SharedMemory(buffer.handle(), false));
-  if (!shm->Map(buffer.size())) {
+  scoped_ptr<SharedMemoryRegion> shm(new SharedMemoryRegion(buffer, false));
+  if (!shm->Map()) {
     NOTIFY_ERROR(kPlatformFailureError, "Failed mapping shared memory.");
     return;
   }
 
   scoped_ptr<BitstreamBufferRef> buffer_ref(
-      new BitstreamBufferRef(buffer.id(), std::move(shm), buffer.size()));
+      new BitstreamBufferRef(buffer.id(), std::move(shm)));
 
   encoder_thread_task_runner_->PostTask(
       FROM_HERE,