4 files changed, 39 insertions, 1 deletions
diff --git a/content/browser/gpu/gpu_process_host_ui_shim.cc b/content/browser/gpu/gpu_process_host_ui_shim.cc
index eda47e1..8608ee5 100644
--- a/content/browser/gpu/gpu_process_host_ui_shim.cc
+++ b/content/browser/gpu/gpu_process_host_ui_shim.cc
@@ -7,10 +7,12 @@
 #include <algorithm>
 
 #include "base/bind.h"
-#include "base/debug/trace_event.h"
+#include "base/command_line.h"
 #include "base/id_map.h"
 #include "base/lazy_instance.h"
 #include "base/process_util.h"
+#include "base/string_number_conversions.h"
+#include "base/debug/trace_event.h"
 #include "content/browser/gpu/gpu_data_manager_impl.h"
 #include "content/browser/gpu/gpu_process_host.h"
 #include "content/browser/gpu/gpu_surface_tracker.h"
@@ -19,6 +21,7 @@
 #include "content/common/gpu/gpu_messages.h"
 #include "content/port/browser/render_widget_host_view_port.h"
 #include "content/public/browser/browser_thread.h"
+#include "ui/gfx/gl/gl_switches.h"
 
 #if defined(TOOLKIT_USES_GTK)
 // These two #includes need to come after gpu_messages.h.
@@ -337,6 +340,16 @@ void GpuProcessHostUIShim::OnAcceleratedSurfaceNew(
 
 #endif
 
+static base::TimeDelta GetSwapDelay() {
+  CommandLine* cmd_line = CommandLine::ForCurrentProcess();
+  int delay = 0;
+  if (cmd_line->HasSwitch(switches::kGpuSwapDelay)) {
+    base::StringToInt(cmd_line->GetSwitchValueNative(
+        switches::kGpuSwapDelay).c_str(), &delay);
+  }
+  return base::TimeDelta::FromMilliseconds(delay);
+}
+
 void GpuProcessHostUIShim::OnAcceleratedSurfaceBuffersSwapped(
     const GpuHostMsg_AcceleratedSurfaceBuffersSwapped_Params& params) {
   TRACE_EVENT0("renderer",
@@ -353,6 +366,10 @@ void GpuProcessHostUIShim::OnAcceleratedSurfaceBuffersSwapped(
 
   delayed_send.Cancel();
 
+  static const base::TimeDelta swap_delay = GetSwapDelay();
+  if (swap_delay.ToInternalValue())
+    base::PlatformThread::Sleep(swap_delay);
+
   // View must send ACK message after next composite.
   view->AcceleratedSurfaceBuffersSwapped(params, host_id_);
 }
diff --git a/ui/gfx/gl/gl_switches.cc b/ui/gfx/gl/gl_switches.cc
index 38828f3..4614989 100644
--- a/ui/gfx/gl/gl_switches.cc
+++ b/ui/gfx/gl/gl_switches.cc
@@ -39,6 +39,10 @@ const char kSwiftShaderPath[]               = "swiftshader-path";
 // context will never be lost in any situations, say, a GPU reset.
 const char kGpuNoContextLost[]              = "gpu-no-context-lost";
 
+// Add a delay in milliseconds to the gpu swap buffer completion signal.
+// Simulates a slow GPU.
+const char kGpuSwapDelay[]                  = "gpu-swap-delay";
+
 // Flag used for Linux tests: for desktop GL bindings, try to load this GL
 // library first, but fall back to regular library if loading fails.
 const char kTestGLLib[]                     = "test-gl-lib";
diff --git a/ui/gfx/gl/gl_switches.h b/ui/gfx/gl/gl_switches.h
index 6f4460e..7dc2dc8b 100644
--- a/ui/gfx/gl/gl_switches.h
+++ b/ui/gfx/gl/gl_switches.h
@@ -28,6 +28,7 @@ GL_EXPORT extern const char kDisableGpuVsync[];
 GL_EXPORT extern const char kEnableGPUServiceLogging[];
 GL_EXPORT extern const char kEnableGPUClientLogging[];
 GL_EXPORT extern const char kGpuNoContextLost[];
+GL_EXPORT extern const char kGpuSwapDelay[];
 GL_EXPORT extern const char kUseGL[];
 GL_EXPORT extern const char kSwiftShaderPath[];
 GL_EXPORT extern const char kTestGLLib[];
diff --git a/ui/gfx/surface/accelerated_surface_win.cc b/ui/gfx/surface/accelerated_surface_win.cc
index f2a05bd..c1f0c66 100644
--- a/ui/gfx/surface/accelerated_surface_win.cc
+++ b/ui/gfx/surface/accelerated_surface_win.cc
@@ -11,6 +11,8 @@
 #include "base/bind_helpers.h"
 #include "base/callback.h"
 #include "base/command_line.h"
+#include "base/string_number_conversions.h"
+#include "base/time.h"
 #include "base/debug/trace_event.h"
 #include "base/file_path.h"
 #include "base/lazy_instance.h"
@@ -476,6 +478,16 @@ void AcceleratedPresenter::Invalidate() {
 AcceleratedPresenter::~AcceleratedPresenter() {
 }
 
+static base::TimeDelta GetSwapDelay() {
+  CommandLine* cmd_line = CommandLine::ForCurrentProcess();
+  int delay = 0;
+  if (cmd_line->HasSwitch(switches::kGpuSwapDelay)) {
+    base::StringToInt(cmd_line->GetSwitchValueNative(
+        switches::kGpuSwapDelay).c_str(), &delay);
+  }
+  return base::TimeDelta::FromMilliseconds(delay);
+}
+
 void AcceleratedPresenter::DoPresentAndAcknowledge(
     const gfx::Size& size,
     int64 surface_handle,
@@ -609,6 +621,10 @@ void AcceleratedPresenter::DoPresentAndAcknowledge(
     } while (hr == S_FALSE);
   }
 
+  static const base::TimeDelta swap_delay = GetSwapDelay();
+  if (swap_delay.ToInternalValue())
+    base::PlatformThread::Sleep(swap_delay);
+
   scoped_completion_runner.Release();
   if (!completion_task.is_null())
     completion_task.Run(true);