Mac ÜC: Fix white page hangs

content/browser/renderer_host/render_widget_helper_mac.mm

Index: content/browser/renderer_host/render_widget_helper_mac.mm
diff --git a/content/browser/renderer_host/render_widget_helper_mac.mm b/content/browser/renderer_host/render_widget_helper_mac.mm
index f0d94f43f387ece29c2c2d621016f25bfcaf2bf7..a1ce25cedf334128e5833af641856c3ca06e8c96 100644
--- a/content/browser/renderer_host/render_widget_helper_mac.mm
+++ b/content/browser/renderer_host/render_widget_helper_mac.mm
@@ -21,7 +21,12 @@ namespace content {
 namespace {
 typedef std::map<gfx::AcceleratedWidget,std::pair<int,int>> WidgetMap;
 base::LazyInstance<WidgetMap> g_widget_map;
-base::LazyInstance<base::Lock> g_lock;
+base::LazyInstance<base::Lock> g_widget_map_lock;
+
+typedef std::set<uint64> TokenSet;
+base::LazyInstance<TokenSet> g_token_set;
+uint64 g_token_last_issued = 0;
+base::LazyInstance<base::Lock> g_token_set_lock;
 }  // namespace
 
 // static
@@ -29,7 +34,7 @@ void RenderWidgetHelper::SetRenderWidgetIDForWidget(
     gfx::AcceleratedWidget native_widget,
     int render_process_id,
     int render_widget_id) {
-  base::AutoLock lock(g_lock.Get());
+  base::AutoLock lock(g_widget_map_lock.Get());
   g_widget_map.Get()[native_widget] = std::make_pair(
       render_process_id, render_widget_id);
 }
@@ -37,7 +42,7 @@ void RenderWidgetHelper::SetRenderWidgetIDForWidget(
 // static
 void RenderWidgetHelper::ResetRenderWidgetIDForWidget(
     gfx::AcceleratedWidget native_widget) {
-  base::AutoLock lock(g_lock.Get());
+  base::AutoLock lock(g_widget_map_lock.Get());
   g_widget_map.Get().erase(native_widget);
 }
 
@@ -46,7 +51,7 @@ bool RenderWidgetHelper::GetRenderWidgetIDForWidget(
     gfx::AcceleratedWidget native_widget,
     int* render_process_id,
     int* render_widget_id) {
-  base::AutoLock lock(g_lock.Get());
+  base::AutoLock lock(g_widget_map_lock.Get());
 
   auto found = g_widget_map.Get().find(native_widget);
   if (found != g_widget_map.Get().end()) {
@@ -60,9 +65,24 @@ bool RenderWidgetHelper::GetRenderWidgetIDForWidget(
   return false;
 }
 
+uint64 RenderWidgetHelper::CreateNativeWidgetSwapToken() {
+  base::AutoLock lock(g_token_set_lock.Get());
+  g_token_last_issued += 1;
+  g_token_set.Get().insert(g_token_last_issued);
+  return g_token_last_issued;
+}
+
 // static
 void RenderWidgetHelper::OnNativeSurfaceBuffersSwappedOnUIThread(
     const ViewHostMsg_CompositorSurfaceBuffersSwapped_Params& params) {
+  {
+    base::AutoLock lock(g_token_set_lock.Get());
+    auto found = g_token_set.Get().find(params.native_widget_token);
+    if (found == g_token_set.Get().end())
+      return;
+    g_token_set.Get().erase(found);
+  }
+
   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
   gfx::AcceleratedWidget native_widget =
       content::GpuSurfaceTracker::Get()->AcquireNativeWidget(params.surface_id);