Remove SupportsWeakPtr from GPUTracer and CommandExecutor

GPUTracer and CommandExecutor unnecessarily inherit SupportsWeakPtr.

BUG=None
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.android:android_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel

Review-Url: https://codereview.chromium.org/2892923002
Cr-Commit-Position: refs/heads/master@{#473804}

gpu/command_buffer/service/command_executor.h

@@ -13,7 +13,6 @@
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/memory/shared_memory.h"
-#include "base/memory/weak_ptr.h"
 #include "gpu/command_buffer/service/async_api_interface.h"
 #include "gpu/command_buffer/service/cmd_buffer_engine.h"
 #include "gpu/command_buffer/service/command_buffer_service.h"
@@ -27,8 +26,7 @@ namespace gpu {
 // class should not know about the decoder. Do not add additional dependencies
 // on it.
 class GPU_EXPORT CommandExecutor
-    : NON_EXPORTED_BASE(public CommandBufferEngine),
-      public base::SupportsWeakPtr<CommandExecutor> {
+    : NON_EXPORTED_BASE(public CommandBufferEngine) {
  public:
   static const int kParseCommandsSlice = 20;
 

gpu/command_buffer/service/gpu_tracer.h

@@ -15,7 +15,6 @@
 #include <vector>
 
 #include "base/macros.h"
-#include "base/memory/weak_ptr.h"
 #include "base/threading/thread.h"
 #include "gpu/command_buffer/service/gles2_cmd_decoder.h"
 #include "gpu/gpu_export.h"
@@ -54,8 +53,7 @@ struct TraceMarker {
 };
 
 // Traces GPU Commands.
-class GPU_EXPORT GPUTracer
-    : public base::SupportsWeakPtr<GPUTracer> {
+class GPU_EXPORT GPUTracer {
  public:
   explicit GPUTracer(gles2::GLES2Decoder* decoder);
   virtual ~GPUTracer();