media/gpu shared memory: Update android/ UnalignedSharedMemory.

Uses the new WritableUnalignedMapping class, which changes the ownership
semantics. See the bug for details on the overall plan.

Bug: 849207
Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel
Change-Id: Ie8da3246a5c7036322e72e120c4925cebc451f0e
Reviewed-on: https://chromium-review.googlesource.com/1117685Reviewed-by: Frank Liberato <liberato@chromium.org>
Commit-Queue: Matthew Cary <mattcary@chromium.org>
Cr-Commit-Position: refs/heads/master@{#571427}

media/gpu/android/android_video_decode_accelerator.cc

@@ -247,9 +247,12 @@ static AVDAManager* GetManager() {
 AndroidVideoDecodeAccelerator::BitstreamRecord::BitstreamRecord(
     const BitstreamBuffer& bitstream_buffer)
     : buffer(bitstream_buffer) {
-  if (buffer.id() != -1)
-    memory.reset(
-        new UnalignedSharedMemory(buffer.handle(), buffer.size(), true));
+  if (buffer.id() != -1) {
+    memory.reset(new WritableUnalignedMapping(buffer.handle(), buffer.size(),
+                                              buffer.offset()));
+    // The handle is no longer needed and can be closed.
+    bitstream_buffer.handle().Close();
+  }
 }
 
 AndroidVideoDecodeAccelerator::BitstreamRecord::BitstreamRecord(
@@ -656,16 +659,15 @@ bool AndroidVideoDecodeAccelerator::QueueInput() {
     return true;
   }
 
-  std::unique_ptr<UnalignedSharedMemory> shm;
+  std::unique_ptr<WritableUnalignedMapping> shm;
 
   if (pending_input_buf_index_ == -1) {
     // When |pending_input_buf_index_| is not -1, the buffer is already dequeued
     // from MediaCodec, filled with data and bitstream_buffer.handle() is
     // closed.
     shm = std::move(pending_bitstream_records_.front().memory);
-    auto* buffer = &pending_bitstream_records_.front().buffer;
 
-    if (!shm->MapAt(buffer->offset(), buffer->size())) {
+    if (!shm->IsValid()) {
       NOTIFY_ERROR(UNREADABLE_INPUT, "UnalignedSharedMemory::Map() failed");
       return false;
     }

media/gpu/android/android_video_decode_accelerator.h

@@ -35,7 +35,6 @@
 
 namespace media {
 class AndroidVideoSurfaceChooser;
-class UnalignedSharedMemory;
 class PromotionHintAggregator;
 
 // A VideoDecodeAccelerator implementation for Android. This class decodes the
@@ -305,8 +304,8 @@ class MEDIA_GPU_EXPORT AndroidVideoDecodeAccelerator
 
     BitstreamBuffer buffer;
 
-    // |memory| is not mapped, and may be null if buffer has no data.
-    std::unique_ptr<UnalignedSharedMemory> memory;
+    // |memory| may be null if buffer has no data.
+    std::unique_ptr<WritableUnalignedMapping> memory;
   };
 
   // Encoded bitstream buffers to be passed to media codec, queued until an

media/gpu/android/android_video_encode_accelerator.cc

@@ -429,11 +429,12 @@ void AndroidVideoEncodeAccelerator::DequeueOutput() {
 
   BitstreamBuffer bitstream_buffer = available_bitstream_buffers_.back();
   available_bitstream_buffers_.pop_back();
-  auto shm = std::make_unique<UnalignedSharedMemory>(
-      bitstream_buffer.handle(), bitstream_buffer.size(), false);
-  RETURN_ON_FAILURE(
-      shm->MapAt(bitstream_buffer.offset(), bitstream_buffer.size()),
-      "Failed to map SHM", kPlatformFailureError);
+  auto shm = std::make_unique<WritableUnalignedMapping>(
+      bitstream_buffer.handle(), bitstream_buffer.size(),
+      bitstream_buffer.offset());
+  // The handle is no longer needed and should be closed.
+  bitstream_buffer.handle().Close();
+  RETURN_ON_FAILURE(shm->IsValid(), "Failed to map SHM", kPlatformFailureError);
   RETURN_ON_FAILURE(
       size <= bitstream_buffer.size(),
       "Encoded buffer too large: " << size << ">" << bitstream_buffer.size(),