Render Widget to use default LSI

Previously, ParentLocalSurfaceIdAllocator would default to an invalid
LocalSurfaceId. A new LSI had to be explicitly allocated before the
normal behavior could use it.

With ParentLocalSurfaceIdAllocator now default initializing a valid LSI,
the various call sites no longer need to explicitly check for the
uninitialized state.

Render Widget is one of those call sites.

BUG=837030

Change-Id: I330d2c47492f1ac577a928f20a8e8e4e14f91b29
Reviewed-on: https://chromium-review.googlesource.com/1038127
Commit-Queue: Chris Blume <cblume@chromium.org>
Reviewed-by: Fady Samuel <fsamuel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#585361}

content/browser/renderer_host/render_widget_host_view_child_frame_unittest.cc

@@ -282,7 +282,7 @@ TEST_F(RenderWidgetHostViewChildFrameTest, WasResizedOncePerChange) {
   constexpr gfx::Size compositor_viewport_pixel_size(100, 100);
   constexpr gfx::Rect screen_space_rect(compositor_viewport_pixel_size);
   viz::ParentLocalSurfaceIdAllocator allocator;
-  viz::LocalSurfaceId local_surface_id = allocator.GenerateId();
+  viz::LocalSurfaceId local_surface_id = allocator.GetCurrentLocalSurfaceId();
   constexpr viz::FrameSinkId frame_sink_id(1, 1);
   const viz::SurfaceId surface_id(frame_sink_id, local_surface_id);
 

content/renderer/render_widget_browsertest.cc

@@ -70,7 +70,8 @@ TEST_F(RenderWidgetTest, OnSynchronizeVisualProperties) {
   render_thread_->sink().ClearMessages();
   viz::ParentLocalSurfaceIdAllocator local_surface_id_allocator;
   gfx::Size size(100, 100);
-  visual_properties.local_surface_id = local_surface_id_allocator.GenerateId();
+  visual_properties.local_surface_id =
+      local_surface_id_allocator.GetCurrentLocalSurfaceId();
   visual_properties.new_size = size;
   visual_properties.compositor_viewport_pixel_size = size;
   OnSynchronizeVisualProperties(visual_properties);
@@ -98,23 +99,18 @@ TEST_F(RenderWidgetTest, OnSynchronizeVisualProperties) {
 }
 
 class RenderWidgetInitialSizeTest : public RenderWidgetTest {
- public:
-  RenderWidgetInitialSizeTest() : RenderWidgetTest(), initial_size_(200, 100) {
-    local_surface_id_ = local_surface_id_allocator_.GenerateId();
-  }
-
  protected:
   std::unique_ptr<VisualProperties> InitialVisualProperties() override {
     std::unique_ptr<VisualProperties> initial_visual_properties(
         new VisualProperties());
     initial_visual_properties->new_size = initial_size_;
     initial_visual_properties->compositor_viewport_pixel_size = initial_size_;
-    initial_visual_properties->local_surface_id = local_surface_id_;
+    initial_visual_properties->local_surface_id =
+        local_surface_id_allocator_.GetCurrentLocalSurfaceId();
     return initial_visual_properties;
   }
 
-  gfx::Size initial_size_;
-  viz::LocalSurfaceId local_surface_id_;
+  gfx::Size initial_size_ = gfx::Size(200, 100);
   viz::ParentLocalSurfaceIdAllocator local_surface_id_allocator_;
 };