Remove unused mojo binding.h includes in //media

This CL cleans up unnecessary mojo/public/cpp/bindings/binding.h
includes in //media.

Bug: 955171
Change-Id: I79b71fcf3453e49ef0d4909c7a71d3521f33ae62
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1977894Reviewed-by: Ken Rockot <rockot@google.com>
Reviewed-by: John Rummell <jrummell@chromium.org>
Commit-Queue: Gyuyoung Kim <gyuyoung@igalia.com>
Cr-Commit-Position: refs/heads/master@{#727316}

media/capture/video/mock_device_factory.h

@@ -8,7 +8,6 @@
 #include <map>
 
 #include "media/capture/video/video_capture_device_factory.h"
-#include "mojo/public/cpp/bindings/binding.h"
 
 namespace media {
 

media/learning/mojo/public/cpp/mojo_learning_task_controller.cc

@@ -6,8 +6,6 @@
 
 #include <utility>
 
-#include "mojo/public/cpp/bindings/binding.h"
-
 namespace media {
 namespace learning {
 

media/mojo/services/mojo_cdm_proxy_unittest.cc

@@ -19,7 +19,6 @@
 #include "media/mojo/services/mojo_cdm_proxy.h"
 #include "media/mojo/services/mojo_cdm_proxy_service.h"
 #include "media/mojo/services/mojo_cdm_service_context.h"
-#include "mojo/public/cpp/bindings/binding.h"
 #include "mojo/public/cpp/bindings/interface_request.h"
 #include "mojo/public/cpp/bindings/receiver.h"
 #include "testing/gtest/include/gtest/gtest.h"