(not for review) Add overhang resource

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 b8801d82c4374b85f26f3ae0ef22ce0f232f9c91..7c8135d0304d5c31fabb52c69711d7c719d3a508 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -37,6 +37,7 @@
 #include "cc/quads/render_pass_draw_quad.h"
 #include "cc/quads/shared_quad_state.h"
 #include "cc/quads/solid_color_draw_quad.h"
+#include "cc/quads/texture_draw_quad.h"
 #include "cc/resources/memory_history.h"
 #include "cc/resources/picture_layer_tiling.h"
 #include "cc/resources/prioritized_resource_manager.h"
@@ -197,6 +198,8 @@ LayerTreeHostImpl::LayerTreeHostImpl(
       zero_budget_(false),
       device_scale_factor_(1.f),
       overdraw_bottom_height_(0.f),
+      overhang_ui_resource_id_(0),
+      overhang_image_size_(0, 0),
       external_stencil_test_enabled_(false),
       animation_registrar_(AnimationRegistrar::Create()),
       rendering_stats_instrumentation_(rendering_stats_instrumentation),
@@ -503,7 +506,9 @@ static void AppendQuadsToFillScreen(
     RenderPass* target_render_pass,
     LayerImpl* root_layer,
     SkColor screen_background_color,
-    const OcclusionTrackerImpl& occlusion_tracker) {
+    const OcclusionTrackerImpl& occlusion_tracker,
+    ResourceProvider::ResourceId overhang_resource_id,
+    gfx::Size overhang_image_size) {
   if (!root_layer || !SkColorGetA(screen_background_color))
     return;
 
@@ -550,9 +555,35 @@ static void AppendQuadsToFillScreen(
         MathUtil::MapClippedRect(transform_to_layer_space, fill_rects.rect());
     // Skip the quad culler and just append the quads directly to avoid
     // occlusion checks.
-    scoped_ptr<SolidColorDrawQuad> quad = SolidColorDrawQuad::Create();
-    quad->SetNew(shared_quad_state, layer_rect, screen_background_color, false);
-    quad_culler.Append(quad.PassAs<DrawQuad>(), &append_quads_data);
+    if (overhang_resource_id) {
+      scoped_ptr<TextureDrawQuad> tex_quad = TextureDrawQuad::Create();
+      const float vertex_opacity[4] = {1.f, 1.f, 1.f, 1.f};
+      tex_quad->SetNew(
+          shared_quad_state,
+          layer_rect,
+          layer_rect,
+          overhang_resource_id,
+          false,
+          gfx::PointF(
+              layer_rect.x() /
+                static_cast<float>(overhang_image_size.width()),
+              layer_rect.y() /
+                  static_cast<float>(overhang_image_size.height())),
+          gfx::PointF(
+              (layer_rect.x() + layer_rect.width()) /
+                static_cast<float>(overhang_image_size.width()),
+              (layer_rect.y() + layer_rect.height()) /
+                  static_cast<float>(overhang_image_size.height())),
+          screen_background_color,
+          vertex_opacity,
+          false);
+      quad_culler.Append(tex_quad.PassAs<DrawQuad>(), &append_quads_data);
+    } else {
+      scoped_ptr<SolidColorDrawQuad> quad = SolidColorDrawQuad::Create();
+      quad->SetNew(
+          shared_quad_state, layer_rect, screen_background_color, false);
+      quad_culler.Append(quad.PassAs<DrawQuad>(), &append_quads_data);
+    }
   }
 }
 
@@ -767,7 +798,9 @@ bool LayerTreeHostImpl::CalculateRenderPasses(FrameData* frame) {
     AppendQuadsToFillScreen(frame->render_passes.back(),
                             active_tree_->root_layer(),
                             active_tree_->background_color(),
-                            occlusion_tracker);
+                            occlusion_tracker,
+                            ResourceIdForUIResource(overhang_ui_resource_id_),
+                            overhang_image_size_);
   }
 
   if (draw_frame)
@@ -1738,6 +1771,12 @@ void LayerTreeHostImpl::SetOverdrawBottomHeight(float overdraw_bottom_height) {
   SetFullRootLayerDamage();
 }
 
+void LayerTreeHostImpl::SetOverhangUIResource(
+    UIResourceId overhang_ui_resource_id, gfx::Size overhang_image_size) {
+  overhang_ui_resource_id_ = overhang_ui_resource_id;
+  overhang_image_size_ = overhang_image_size;
+}
+
 void LayerTreeHostImpl::SetDeviceScaleFactor(float device_scale_factor) {
   if (device_scale_factor == device_scale_factor_)
     return;