content: Remove gpu memory buffer manager from ChildThreadImpl.

content/child/child_thread_impl.cc

Index: content/child/child_thread_impl.cc
diff --git a/content/child/child_thread_impl.cc b/content/child/child_thread_impl.cc
index 3b534c22097ec72dedeaf8c4cffe7fd584c18f30..84261823a3351dc24057d20307c45a7db93680b2 100644
--- a/content/child/child_thread_impl.cc
+++ b/content/child/child_thread_impl.cc
@@ -34,7 +34,6 @@
 #include "build/build_config.h"
 #include "components/tracing/child/child_trace_message_filter.h"
 #include "content/child/child_discardable_shared_memory_manager.h"
-#include "content/child/child_gpu_memory_buffer_manager.h"
 #include "content/child/child_histogram_message_filter.h"
 #include "content/child/child_process.h"
 #include "content/child/child_resource_message_filter.h"
@@ -605,9 +604,6 @@ void ChildThreadImpl::Init(const Options& options) {
   shared_bitmap_manager_.reset(
       new ChildSharedBitmapManager(thread_safe_sender()));
 
-  gpu_memory_buffer_manager_.reset(
-      new ChildGpuMemoryBufferManager(thread_safe_sender()));
-
   discardable_shared_memory_manager_.reset(
       new ChildDiscardableSharedMemoryManager(thread_safe_sender()));
 }