Make RenderPass::Id an isolated class

cc/output/direct_renderer.cc

Index: cc/output/direct_renderer.cc
diff --git a/cc/output/direct_renderer.cc b/cc/output/direct_renderer.cc
index 8b7277b066e9df538f0c06f978ff1decf75a4574..3ec22059ed16589a4985fe0a89e70f3e2d49d2d1 100644
--- a/cc/output/direct_renderer.cc
+++ b/cc/output/direct_renderer.cc
@@ -148,19 +148,19 @@ void DirectRenderer::DecideRenderPassAllocationsForFrame(
   if (!resource_provider_)
     return;
 
-  base::hash_map<RenderPass::Id, gfx::Size> render_passes_in_frame;
+  base::hash_map<RenderPassId, gfx::Size> render_passes_in_frame;
   for (size_t i = 0; i < render_passes_in_draw_order.size(); ++i)
-    render_passes_in_frame.insert(std::pair<RenderPass::Id, gfx::Size>(
+    render_passes_in_frame.insert(std::pair<RenderPassId, gfx::Size>(
         render_passes_in_draw_order[i]->id,
         RenderPassTextureSize(render_passes_in_draw_order[i])));
 
-  std::vector<RenderPass::Id> passes_to_delete;
-  base::ScopedPtrHashMap<RenderPass::Id, ScopedResource>::const_iterator
+  std::vector<RenderPassId> passes_to_delete;
+  base::ScopedPtrHashMap<RenderPassId, ScopedResource>::const_iterator
       pass_iter;
   for (pass_iter = render_pass_textures_.begin();
        pass_iter != render_pass_textures_.end();
        ++pass_iter) {
-    base::hash_map<RenderPass::Id, gfx::Size>::const_iterator it =
+    base::hash_map<RenderPassId, gfx::Size>::const_iterator it =
         render_passes_in_frame.find(pass_iter->first);
     if (it == render_passes_in_frame.end()) {
       passes_to_delete.push_back(pass_iter->first);
@@ -415,8 +415,7 @@ bool DirectRenderer::UseRenderPass(DrawingFrame* frame,
   return BindFramebufferToTexture(frame, texture, render_pass->output_rect);
 }
 
-bool DirectRenderer::HasAllocatedResourcesForTesting(RenderPass::Id id)
-    const {
+bool DirectRenderer::HasAllocatedResourcesForTesting(RenderPassId id) const {
   ScopedResource* texture = render_pass_textures_.get(id);
   return texture && texture->id();
 }