Add gpu::MailboxHolder to hold state for a gpu::Mailbox

cc/resources/resource_provider.cc

Index: cc/resources/resource_provider.cc
diff --git a/cc/resources/resource_provider.cc b/cc/resources/resource_provider.cc
index f5d365f1a9e22beac6f14418b29558b130450f2e..31a0644fcb9e4b9618c78ce3697700017f1397ba 100644
--- a/cc/resources/resource_provider.cc
+++ b/cc/resources/resource_provider.cc
@@ -549,7 +549,7 @@ void ResourceProvider::DeleteResourceInternal(ResourceMap::iterator it,
     GLC(context3d, context3d->deleteBuffer(resource->gl_pixel_buffer_id));
   }
   if (resource->mailbox.IsValid() && resource->external) {
-    unsigned sync_point = resource->mailbox.sync_point();
+    uint32 sync_point = resource->mailbox.sync_point();
     if (resource->mailbox.IsTexture()) {
       lost_resource |= lost_output_surface_;
       WebGraphicsContext3D* context3d = Context3d();
@@ -745,13 +745,13 @@ const ResourceProvider::Resource* ResourceProvider::LockForRead(ResourceId id) {
       if (resource->mailbox.sync_point()) {
         GLC(context3d,
             context3d->waitSyncPoint(resource->mailbox.sync_point()));
-        resource->mailbox.ResetSyncPoint();
+        resource->mailbox.set_sync_point(0);
       }
       resource->gl_id = texture_id_allocator_->NextId();
       GLC(context3d, context3d->bindTexture(resource->target, resource->gl_id));
       GLC(context3d,
           context3d->consumeTextureCHROMIUM(resource->target,
-                                            resource->mailbox.data()));
+                                            resource->mailbox.mailbox().name));
     }
   }
 
@@ -1044,7 +1044,7 @@ void ResourceProvider::PrepareSendToParent(const ResourceIdArray& resources,
     list->push_back(resource);
   }
   if (need_sync_point) {
-    unsigned int sync_point = context3d->insertSyncPoint();
+    uint32 sync_point = context3d->insertSyncPoint();
     for (TransferableResourceArray::iterator it = list->begin();
          it != list->end();
          ++it) {
@@ -1117,7 +1117,7 @@ void ResourceProvider::ReceiveFromChild(
                           GL_CLAMP_TO_EDGE,
                           TextureUsageAny,
                           it->format);
-      resource.mailbox.SetName(it->mailbox);
+      resource.mailbox = cc::TextureMailbox(it->mailbox, it->target, 0);
     }
     resource.child_id = child;
     // Don't allocate a texture for a child.
@@ -1220,8 +1220,7 @@ void ResourceProvider::ReceiveReturnsFromParent(
       if (returned.sync_point)
         GLC(context3d, context3d->waitSyncPoint(returned.sync_point));
     } else if (!resource->shared_bitmap) {
-      resource->mailbox =
-          TextureMailbox(resource->mailbox.name(), returned.sync_point);
+      resource->mailbox.set_sync_point(returned.sync_point);
     }
 
     if (!resource->marked_for_deletion)
@@ -1285,14 +1284,15 @@ void ResourceProvider::TransferResource(WebGraphicsContext3D* context,
     GLC(context,
         context->produceTextureCHROMIUM(resource->target,
                                         resource->mailbox.name));
-    source->mailbox.SetName(resource->mailbox);
+    source->mailbox =
+        cc::TextureMailbox(resource->mailbox, resource->target, 0);
   } else {
     DCHECK(source->mailbox.IsTexture());
     // This is either an external resource, or a compositor resource that we
     // already exported. Make sure to forward the sync point that we were given.
-    resource->mailbox = source->mailbox.name();
+    resource->mailbox = source->mailbox.mailbox();
     resource->sync_point = source->mailbox.sync_point();
-    source->mailbox.ResetSyncPoint();
+    source->mailbox.set_sync_point(0);
   }
 }
 
@@ -1373,7 +1373,7 @@ void ResourceProvider::DeleteAndReturnUnusedResourcesToChild(
   }
   if (need_sync_point) {
     DCHECK(context3d);
-    unsigned int sync_point = context3d->insertSyncPoint();
+    uint32 sync_point = context3d->insertSyncPoint();
     for (size_t i = 0; i < to_return.size(); ++i) {
       if (!to_return[i].sync_point)
         to_return[i].sync_point = sync_point;