GVDAH: fix crash on Android caused by invalid assumption of reentrancy on hash_map<>.

content/common/gpu/client/gpu_video_encode_accelerator_host.cc

 // Copyright 2013 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 "content/common/gpu/client/gpu_video_encode_accelerator_host.h"
 
 #include "base/logging.h"
 #include "base/message_loop/message_loop_proxy.h"
 #include "content/common/gpu/client/gpu_channel_host.h"
 #include "content/common/gpu/gpu_messages.h"
@@ skipping 159 matching lines @@
            << ", input_coded_size=" << input_coded_size.ToString()
            << ", output_buffer_size=" << output_buffer_size;
   if (client_) {
     client_->RequireBitstreamBuffers(
         input_count, input_coded_size, output_buffer_size);
   }
 }
 
 void GpuVideoEncodeAcceleratorHost::OnNotifyInputDone(int32 frame_id) {
   DVLOG(3) << "OnNotifyInputDone(): frame_id=" << frame_id;
+  // Fun-fact: std::hash_map is not spec'd to be re-entrant; since freeing a
+  // frame can trigger a further encode to be kicked off and thus an .insert()
+  // back into the map, we separate the frame's dtor running from the .erase()
+  // running by holding on to the frame temporarily.  This isn't "just
+  // theoretical" - Android's std::hash_map crashes if we don't do this.
+  scoped_refptr<media::VideoFrame> frame = frame_map_[frame_id];
   if (!frame_map_.erase(frame_id)) {
     DLOG(ERROR) << "OnNotifyInputDone(): "
                    "invalid frame_id=" << frame_id;
     // See OnNotifyError for why this needs to be the last thing in this
     // function.
     OnNotifyError(kPlatformFailureError);
     return;
   }
+  frame = NULL;  // Not necessary but nice to be explicit; see fun-fact above.
 }
 
 void GpuVideoEncodeAcceleratorHost::OnBitstreamBufferReady(
     int32 bitstream_buffer_id,
     uint32 payload_size,
     bool key_frame) {
   DVLOG(3) << "OnBitstreamBufferReady(): "
               "bitstream_buffer_id=" << bitstream_buffer_id
            << ", payload_size=" << payload_size
            << ", key_frame=" << key_frame;
@@ skipping 20 matching lines @@
     delete message;
     NotifyError(kPlatformFailureError);
   } else if (!channel_->Send(message)) {
     DLOG(ERROR) << "Send(): sending failed: message->type()="
                 << message->type();
     NotifyError(kPlatformFailureError);
   }
 }
 
 }  // namespace content