Android media: Move back to legacy UnalignedSharedMemory.

There are crashes appearing where a read-only shared memory region is
being used instead of the expected writable region. While we track that
down, this CL reverts the android video {en/de}coding to the legacy
implementation.

Bug: 838365
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: I699913801d9384b55f3f382519207f24d8ed17da
Tested: android media_unittests
TBR: liberato@chromium.org,alexilin@chromium.org
Reviewed-on: https://chromium-review.googlesource.com/1219226Reviewed-by: Matthew Cary <mattcary@chromium.org>
Reviewed-by: Alexandr Ilin <alexilin@chromium.org>
Commit-Queue: Matthew Cary <mattcary@chromium.org>
Cr-Commit-Position: refs/heads/master@{#590290}

media/gpu/android/android_video_decode_accelerator.cc

@@ -247,10 +247,8 @@ AndroidVideoDecodeAccelerator::BitstreamRecord::BitstreamRecord(
     const BitstreamBuffer& bitstream_buffer)
     : buffer(bitstream_buffer) {
   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();
+    memory.reset(
+        new UnalignedSharedMemory(buffer.handle(), buffer.size(), true));
   }
 }
 
@@ -648,15 +646,16 @@ bool AndroidVideoDecodeAccelerator::QueueInput() {
     return true;
   }
 
-  std::unique_ptr<WritableUnalignedMapping> shm;
+  std::unique_ptr<UnalignedSharedMemory> 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->IsValid()) {
+    if (!shm->MapAt(buffer->offset(), buffer->size())) {
       NOTIFY_ERROR(UNREADABLE_INPUT, "UnalignedSharedMemory::Map() failed");
       return false;
     }

media/gpu/android/android_video_decode_accelerator.h

@@ -305,7 +305,7 @@ class MEDIA_GPU_EXPORT AndroidVideoDecodeAccelerator
     BitstreamBuffer buffer;
 
     // |memory| may be null if buffer has no data.
-    std::unique_ptr<WritableUnalignedMapping> memory;
+    std::unique_ptr<UnalignedSharedMemory> memory;
   };
 
   // Encoded bitstream buffers to be passed to media codec, queued until an

media/gpu/android/android_video_encode_accelerator.cc

@@ -424,12 +424,11 @@ void AndroidVideoEncodeAccelerator::DequeueOutput() {
 
   BitstreamBuffer bitstream_buffer = available_bitstream_buffers_.back();
   available_bitstream_buffers_.pop_back();
-  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);
+  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);
   RETURN_ON_FAILURE(
       size <= bitstream_buffer.size(),
       "Encoded buffer too large: " << size << ">" << bitstream_buffer.size(),