Replace deprecated base::NonThreadSafe in /content/renderer/gpu in favor of ThreadChecker.

content/renderer/gpu/compositor_external_begin_frame_source.h

Index: content/renderer/gpu/compositor_external_begin_frame_source.h
diff --git a/content/renderer/gpu/compositor_external_begin_frame_source.h b/content/renderer/gpu/compositor_external_begin_frame_source.h
index 96520a0210d9cfa3a1db2ebc42d1219699295f7e..7765a675723ed40701be16826632058e9e0182e1 100644
--- a/content/renderer/gpu/compositor_external_begin_frame_source.h
+++ b/content/renderer/gpu/compositor_external_begin_frame_source.h
@@ -10,7 +10,7 @@
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
-#include "base/threading/non_thread_safe.h"
+#include "base/threading/thread_checker.h"
 #include "cc/scheduler/begin_frame_source.h"
 #include "content/renderer/gpu/compositor_forwarding_message_filter.h"
 
@@ -31,8 +31,7 @@ namespace content {
 // directly rather than proxied by this class.
 class CompositorExternalBeginFrameSource
     : public cc::BeginFrameSource,
-      public cc::ExternalBeginFrameSourceClient,
-      public NON_EXPORTED_BASE(base::NonThreadSafe) {
+      public cc::ExternalBeginFrameSourceClient {
  public:
   explicit CompositorExternalBeginFrameSource(
       CompositorForwardingMessageFilter* filter,
@@ -88,6 +87,8 @@ class CompositorExternalBeginFrameSource
   int routing_id_;
   CompositorForwardingMessageFilter::Handler begin_frame_source_filter_handler_;
 
+  THREAD_CHECKER(thread_checker_);
+
   DISALLOW_COPY_AND_ASSIGN(CompositorExternalBeginFrameSource);
 };