Fix -Wdefaulted-function-deleted in fuchsia_video_decoder.cc

Previous Clang versions would only error about a defaulted function
being deleted when they're *used*. This warning highlights the problem
up-front.

../../media/filters/fuchsia/fuchsia_video_decoder.cc:156:3: error: explicitly
defaulted move constructor is implicitly deleted
[-Werror,-Wdefaulted-function-deleted]
  InputBuffer(InputBuffer&& other) = default;
  ^
../../media/filters/fuchsia/fuchsia_video_decoder.cc:202:15: note: move
constructor of 'InputBuffer' is implicitly deleted because field 'buffer_' has
a deleted move constructor
  CodecBuffer buffer_;
              ^
../../media/filters/fuchsia/fuchsia_video_decoder.cc:147:28: note:
'CodecBuffer' has been explicitly marked deleted here
  DISALLOW_COPY_AND_ASSIGN(CodecBuffer);
                           ^

../../media/filters/fuchsia/fuchsia_video_decoder.cc:221:3: error: explicitly
defaulted move constructor is implicitly deleted
[-Werror,-Wdefaulted-function-deleted]
  OutputBuffer(OutputBuffer&& other) = default;
  ^
../../media/filters/fuchsia/fuchsia_video_decoder.cc:217:22: note: move
constructor of 'OutputBuffer' is implicitly deleted because base class
'base::RefCountedThreadSafe<OutputBuffer>' has a deleted move constructor
class OutputBuffer : public base::RefCountedThreadSafe<OutputBuffer> {
                     ^
../../base/memory/ref_counted.h:425:28: note: 'RefCountedThreadSafe' has been
explicitly marked deleted here
  DISALLOW_COPY_AND_ASSIGN(RefCountedThreadSafe);
                           ^

Bug: 890307
Change-Id: I9f8751735e09cb3ec0f6f4c400f8964194bd8937
Reviewed-on: https://chromium-review.googlesource.com/c/1348031Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Hans Wennborg <hans@chromium.org>
Cr-Commit-Position: refs/heads/master@{#610403}

media/filters/fuchsia/fuchsia_video_decoder.cc

@@ -153,9 +153,6 @@ class InputBuffer {
 
   ~InputBuffer() { CallDecodeCallbackIfAny(DecodeStatus::ABORTED); }
 
-  InputBuffer(InputBuffer&& other) = default;
-  InputBuffer& operator=(InputBuffer&& other) = default;
-
   bool Initialize(
       const fuchsia::mediacodec::CodecBufferConstraints& constraints) {
     return buffer_.Initialize(constraints);
@@ -218,9 +215,6 @@ class OutputBuffer : public base::RefCountedThreadSafe<OutputBuffer> {
  public:
   OutputBuffer() = default;
 
-  OutputBuffer(OutputBuffer&& other) = default;
-  OutputBuffer& operator=(OutputBuffer&& other) = default;
-
   bool Initialize(
       const fuchsia::mediacodec::CodecBufferConstraints& constraints) {
     if (!buffer_.Initialize(constraints)) {