Add PERSISTENT_MAP usage for GpuMemoryBuffers.

cc/trees/layer_tree_host_impl.cc

Index: cc/trees/layer_tree_host_impl.cc
diff --git a/cc/trees/layer_tree_host_impl.cc b/cc/trees/layer_tree_host_impl.cc
index d421f84b00c7418f24d41fda48980fa37ef86b96..dfb97d8bf7d7134b63b4108f669e162f93630d1f 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -2107,17 +2107,27 @@ void LayerTreeHostImpl::CreateResourceAndTileTaskWorkerPool(
   }
 
   if (GetRendererCapabilities().using_image) {
-    unsigned image_target = settings_.use_image_texture_target;
+    unsigned map_image_target = settings_.map_image_texture_target;
     DCHECK_IMPLIES(
-        image_target == GL_TEXTURE_RECTANGLE_ARB,
+        map_image_target == GL_TEXTURE_RECTANGLE_ARB,
         context_provider->ContextCapabilities().gpu.texture_rectangle);
     DCHECK_IMPLIES(
-        image_target == GL_TEXTURE_EXTERNAL_OES,
+        map_image_target == GL_TEXTURE_EXTERNAL_OES,
+        context_provider->ContextCapabilities().gpu.egl_image_external);
+    unsigned persistent_map_image_target =
+        settings_.persistent_map_image_texture_target;
+    DCHECK_IMPLIES(
+        persistent_map_image_target == GL_TEXTURE_RECTANGLE_ARB,
+        context_provider->ContextCapabilities().gpu.texture_rectangle);
+    DCHECK_IMPLIES(
+        persistent_map_image_target == GL_TEXTURE_EXTERNAL_OES,
         context_provider->ContextCapabilities().gpu.egl_image_external);
 
     if (settings_.use_zero_copy || IsSynchronousSingleThreaded()) {
+      // TODO(danakj): ZeroCopy doesn't support partial updates. Use
+      // persistent_map_image_target when it does. crbug.com/487387
       *resource_pool =
-          ResourcePool::Create(resource_provider_.get(), image_target);
+          ResourcePool::Create(resource_provider_.get(), map_image_target);
 
       *tile_task_worker_pool = ZeroCopyTileTaskWorkerPool::Create(
           task_runner, task_graph_runner, resource_provider_.get());
@@ -2126,8 +2136,10 @@ void LayerTreeHostImpl::CreateResourceAndTileTaskWorkerPool(
 
     if (settings_.use_one_copy) {
       // We need to create a staging resource pool when using copy rasterizer.
+      // TODO(danakj): OneCopy doesn't support partial updates. Use
+      // persistent_map_image_target when it does. crbug.com/487387
       *staging_resource_pool =
-          ResourcePool::Create(resource_provider_.get(), image_target);
+          ResourcePool::Create(resource_provider_.get(), map_image_target);
       *resource_pool =
           ResourcePool::Create(resource_provider_.get(), GL_TEXTURE_2D);