cc: Fix negative integer overflow in RenderPass serialization code.

cc/ipc/struct_traits_unittest.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/message_loop/message_loop.h"
 #include "cc/input/selection.h"
 #include "cc/ipc/traits_test_service.mojom.h"
 #include "cc/quads/debug_border_draw_quad.h"
 #include "cc/quads/render_pass.h"
 #include "cc/quads/render_pass_draw_quad.h"
@@ skipping 648 matching lines @@
             out_color_quad->force_anti_aliasing_off);
 
   const SurfaceDrawQuad* out_surface_quad =
       SurfaceDrawQuad::MaterialCast(output->quad_list.ElementAt(2));
   EXPECT_EQ(out_surface_quad->shared_quad_state, out_sqs2);
   EXPECT_EQ(surface_quad->rect, out_surface_quad->rect);
   EXPECT_EQ(surface_quad->visible_rect, out_surface_quad->visible_rect);
   EXPECT_EQ(surface_quad->surface_id, out_surface_quad->surface_id);
 }
 
+TEST_F(StructTraitsTest, RenderPassWithEmptySharedQuadStateList) {
+  const RenderPassId id(3, 2);
+  const gfx::Rect output_rect(45, 22, 120, 13);
+  const gfx::Transform transform_to_root =
+      gfx::Transform(1.0, 0.5, 0.5, -0.5, -1.0, 0.0);
+  const gfx::Rect damage_rect(56, 123, 19, 43);
+  const bool has_transparent_background = true;
+  std::unique_ptr<RenderPass> input = RenderPass::Create();
+  input->SetAll(id, output_rect, damage_rect, transform_to_root,
+                has_transparent_background);
+
+  // Unlike the previous test, don't add any quads to the list; we need to
+  // verify that the serialization code can deal with that.
+  std::unique_ptr<RenderPass> output;
+  mojom::TraitsTestServicePtr proxy = GetTraitsTestProxy();
+  proxy->EchoRenderPass(input, &output);
+
+  EXPECT_EQ(input->quad_list.size(), output->quad_list.size());
+  EXPECT_EQ(input->shared_quad_state_list.size(),
+            output->shared_quad_state_list.size());
+  EXPECT_EQ(id, output->id);
+  EXPECT_EQ(output_rect, output->output_rect);
+  EXPECT_EQ(damage_rect, output->damage_rect);
+  EXPECT_EQ(transform_to_root, output->transform_to_root_target);
+  EXPECT_EQ(has_transparent_background, output->has_transparent_background);
+}
+
 TEST_F(StructTraitsTest, RenderPassId) {
   const int layer_id = 1337;
   const uint32_t index = 0xdeadbeef;
   RenderPassId input(layer_id, index);
   mojom::TraitsTestServicePtr proxy = GetTraitsTestProxy();
   RenderPassId output;
   proxy->EchoRenderPassId(input, &output);
   EXPECT_EQ(layer_id, output.layer_id);
   EXPECT_EQ(index, output.index);
 }
@@ skipping 198 matching lines @@
   EXPECT_EQ(y_plane_resource_id, out_quad->y_plane_resource_id());
   EXPECT_EQ(u_plane_resource_id, out_quad->u_plane_resource_id());
   EXPECT_EQ(v_plane_resource_id, out_quad->v_plane_resource_id());
   EXPECT_EQ(a_plane_resource_id, out_quad->a_plane_resource_id());
   EXPECT_EQ(color_space, out_quad->color_space);
   EXPECT_EQ(resource_offset, out_quad->resource_offset);
   EXPECT_EQ(resource_multiplier, out_quad->resource_multiplier);
 }
 
 }  // namespace cc