win: Move DXVAVideoDecodeAccelerator's WeakPtrFactory member to the end.

Also fix initialization of weak_ptr_ which I had unintentionally broken in
https://codereview.chromium.org/1103713003

BUG=303818, 467287

Review URL: https://codereview.chromium.org/1111903002

Cr-Commit-Position: refs/heads/master@{#327366}

content/common/gpu/media/dxva_video_decode_accelerator.cc

@@ -522,12 +522,12 @@ DXVAVideoDecodeAccelerator::DXVAVideoDecodeAccelerator(
       make_context_current_(make_context_current),
       codec_(media::kUnknownVideoCodec),
       decoder_thread_("DXVAVideoDecoderThread"),
-      weak_ptr_(weak_this_factory_.GetWeakPtr()),
       pending_flush_(false),
       use_dx11_(false),
       dx11_video_format_converter_media_type_needs_init_(true),
       gl_context_(gl_context),
       weak_this_factory_(this) {
+  weak_ptr_ = weak_this_factory_.GetWeakPtr();
   memset(&input_stream_info_, 0, sizeof(input_stream_info_));
   memset(&output_stream_info_, 0, sizeof(output_stream_info_));
 }

content/common/gpu/media/dxva_video_decode_accelerator.h

@@ -343,14 +343,11 @@ class CONTENT_EXPORT DXVAVideoDecodeAccelerator
   // Used to synchronize access between the decoder thread and the main thread.
   base::Lock decoder_lock_;
 
-  // WeakPtrFactory for posting tasks back to |this|.
-  base::WeakPtrFactory<DXVAVideoDecodeAccelerator> weak_this_factory_;
-
   // Disallow rebinding WeakReference ownership to a different thread by
   // keeping a persistent reference. This avoids problems with the
   // thread safety of reaching into this class from multiple threads to
   // attain a WeakPtr.
-  const base::WeakPtr<DXVAVideoDecodeAccelerator> weak_ptr_;
+  base::WeakPtr<DXVAVideoDecodeAccelerator> weak_ptr_;
 
   // Set to true if we are in the context of a Flush operation. Used to prevent
   // multiple flush done notifications being sent out.
@@ -367,6 +364,9 @@ class CONTENT_EXPORT DXVAVideoDecodeAccelerator
   // The GLContext to be used by the decoder.
   scoped_refptr<gfx::GLContext> gl_context_;
 
+  // WeakPtrFactory for posting tasks back to |this|.
+  base::WeakPtrFactory<DXVAVideoDecodeAccelerator> weak_this_factory_;
+
   // Function pointer for the MFCreateDXGIDeviceManager API.
   static CreateDXGIDeviceManager create_dxgi_device_manager_;
 };