cc: Remove use of PassAs() and constructor-casting with scoped_ptr.

Say you have class A and subclass B.

Previously it was required to PassAs() a scoped_ptr<B> into a
scoped_ptr<A>. This is no longer needed, so just use Pass(). For newly
created scoped_ptrs, you can just use make_scoped_ptr always now.

And when you want to return or assign an empty scoped_ptr(), you can
now use nullptr directly.

Also adds PRESUBMIT checks for:
- return scoped<T>(foo). This should be return make_scoped_ptr(foo).
- bar = scoped<T>(foo). This should be return bar = make_scoped_ptr(foo).
- return scoped<T>(). This should be return nullptr.
- bar = scoped<T>(). This should be return bar = nullptr.

This also replaces p.reset() with p = nullptr; But it does not add a
PRESUBMIT check for that because there are things other than scoped_ptr
with a reset() function.

R=enne@chromium.org

Review URL: https://codereview.chromium.org/609663003

Cr-Commit-Position: refs/heads/master@{#297096}

1 files changed, 3 insertions, 4 deletions

diff --git a/cc/trees/single_thread_proxy.cc b/cc/trees/single_thread_proxy.cc
index 97b06bc..b3712b6 100644
--- a/cc/trees/single_thread_proxy.cc
+++ b/cc/trees/single_thread_proxy.cc
@@ -26,8 +26,7 @@ scoped_ptr<Proxy> SingleThreadProxy::Create(
     LayerTreeHostSingleThreadClient* client,
     scoped_refptr<base::SingleThreadTaskRunner> main_task_runner) {
   return make_scoped_ptr(
-             new SingleThreadProxy(layer_tree_host, client, main_task_runner))
-      .PassAs<Proxy>();
+      new SingleThreadProxy(layer_tree_host, client, main_task_runner));
 }
 
 SingleThreadProxy::SingleThreadProxy(
@@ -314,8 +313,8 @@ void SingleThreadProxy::Stop() {
         blocking_main_thread_task_runner());
     layer_tree_host_->DeleteContentsTexturesOnImplThread(
         layer_tree_host_impl_->resource_provider());
-    scheduler_on_impl_thread_.reset();
-    layer_tree_host_impl_.reset();
+    scheduler_on_impl_thread_ = nullptr;
+    layer_tree_host_impl_ = nullptr;
   }
   layer_tree_host_ = NULL;
 }