V4L2VDA: Always check V4L2_EVENT_SRC_CH_RESOLUTION bit

content/common/gpu/media/v4l2_video_decode_accelerator.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <dlfcn.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <linux/videodev2.h>
 #include <poll.h>
 #include <string.h>
@@ skipping 1005 matching lines @@
 bool V4L2VideoDecodeAccelerator::DequeueResolutionChangeEvent() {
   DCHECK_EQ(decoder_thread_.message_loop(), base::MessageLoop::current());
   DCHECK_NE(decoder_state_, kUninitialized);
   DVLOG(3) << "DequeueResolutionChangeEvent()";
 
   struct v4l2_event ev;
   memset(&ev, 0, sizeof(ev));
 
   while (device_->Ioctl(VIDIOC_DQEVENT, &ev) == 0) {
     if (ev.type == V4L2_EVENT_SOURCE_CHANGE) {
-      uint32_t changes = ev.u.src_change.changes;
-      // We used to define source change was always resolution change. The union
-      // |ev.u| is not used and it is zero by default. When using the upstream
-      // version of the resolution event change, we also need to check
-      // |ev.u.src_change.changes| to know what is changed. For API backward
-      // compatibility, event is treated as resolution change when all bits in
-      // |ev.u.src_change.changes| are cleared.
-      if (changes == 0 || (changes & V4L2_EVENT_SRC_CH_RESOLUTION)) {
+      if (ev.u.src_change.changes & V4L2_EVENT_SRC_CH_RESOLUTION) {
         DVLOG(3)
             << "DequeueResolutionChangeEvent(): got resolution change event.";
         return true;
       }
     } else {
       LOG(ERROR) << "DequeueResolutionChangeEvent(): got an event (" << ev.type
                  << ") we haven't subscribed to.";
     }
   }
   return false;
@@ skipping 995 matching lines @@
 
 void V4L2VideoDecodeAccelerator::PictureCleared() {
   DVLOG(3) << "PictureCleared(). clearing count=" << picture_clearing_count_;
   DCHECK_EQ(decoder_thread_.message_loop(), base::MessageLoop::current());
   DCHECK_GT(picture_clearing_count_, 0);
   picture_clearing_count_--;
   SendPictureReady();
 }
 
 }  // namespace content