Add synthetic delay points for latency testing

gpu/command_buffer/service/async_pixel_transfer_manager_idle.cc

Index: gpu/command_buffer/service/async_pixel_transfer_manager_idle.cc
diff --git a/gpu/command_buffer/service/async_pixel_transfer_manager_idle.cc b/gpu/command_buffer/service/async_pixel_transfer_manager_idle.cc
index 88aff575b0816edcf20b692ced4140029b63f497..680f638bcdbc0aaffd23ff79be4e5213add459aa 100644
--- a/gpu/command_buffer/service/async_pixel_transfer_manager_idle.cc
+++ b/gpu/command_buffer/service/async_pixel_transfer_manager_idle.cc
@@ -6,6 +6,7 @@
 
 #include "base/bind.h"
 #include "base/debug/trace_event.h"
+#include "base/debug/trace_event_synthetic_delay.h"
 #include "base/lazy_instance.h"
 #include "base/memory/weak_ptr.h"
 #include "gpu/command_buffer/service/safe_shared_memory_pool.h"
@@ -168,6 +169,7 @@ void AsyncPixelTransferDelegateIdle::PerformAsyncTexImage2D(
   TRACE_EVENT2("gpu", "PerformAsyncTexImage2D",
                "width", tex_params.width,
                "height", tex_params.height);
+  TRACE_EVENT_SYNTHETIC_DELAY_ACTIVATE("gpu.AsyncTexImage");
 
   void* data = GetAddress(safe_shared_memory, mem_params);
 
@@ -204,6 +206,7 @@ void AsyncPixelTransferDelegateIdle::PerformAsyncTexSubImage2D(
   TRACE_EVENT2("gpu", "PerformAsyncTexSubImage2D",
                "width", tex_params.width,
                "height", tex_params.height);
+  TRACE_EVENT_SYNTHETIC_DELAY_ACTIVATE("gpu.AsyncTexImage");
 
   void* data = GetAddress(safe_shared_memory, mem_params);
 
@@ -319,6 +322,9 @@ void AsyncPixelTransferManagerIdle::ProcessMorePendingTransfers() {
   shared_state_.tasks.front().task.Run();
   shared_state_.tasks.pop_front();
 
+  if (shared_state_.tasks.size() == 1)
+    TRACE_EVENT_SYNTHETIC_DELAY_APPLY("gpu.AsyncTexImage");
+
   shared_state_.ProcessNotificationTasks();
 }