ui: Make the aura_demo not have solid colors in its layers.

ui/aura/demo/demo_main.cc

 // Copyright (c) 2012 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/at_exit.h"
 #include "base/command_line.h"
 #include "base/i18n/icu_util.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop/message_loop.h"
 #include "base/power_monitor/power_monitor.h"
 #include "base/power_monitor/power_monitor_device_source.h"
 #include "third_party/skia/include/core/SkXfermode.h"
 #include "ui/aura/client/default_capture_client.h"
 #include "ui/aura/client/window_tree_client.h"
 #include "ui/aura/env.h"
 #include "ui/aura/test/test_focus_client.h"
 #include "ui/aura/test/test_screen.h"
 #include "ui/aura/window.h"
 #include "ui/aura/window_delegate.h"
 #include "ui/aura/window_tree_host.h"
 #include "ui/base/hit_test.h"
 #include "ui/compositor/test/in_process_context_factory.h"
 #include "ui/events/event.h"
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/geometry/rect.h"
+#include "ui/gfx/skia_util.h"
 #include "ui/gl/gl_surface.h"
 
 #if defined(USE_X11)
 #include "ui/gfx/x/x11_connection.h"
 #endif
 
 #if defined(OS_WIN)
 #include "ui/gfx/win/dpi.h"
 #endif
 
@@ skipping 20 matching lines @@
   }
   bool ShouldDescendIntoChildForEventHandling(
       aura::Window* child,
       const gfx::Point& location) override {
     return true;
   }
   bool CanFocus() override { return true; }
   void OnCaptureLost() override {}
   void OnPaint(gfx::Canvas* canvas) override {
     canvas->DrawColor(color_, SkXfermode::kSrc_Mode);
+    gfx::Rect r;
+    canvas->GetClipBounds(&r);
+    while (!r.IsEmpty()) {

[sky, 2015/02/28 17:32:16]

This is worth a comment. Also, might the region be smaller than 2x2?

[danakj, 2015/03/02 20:12:03]

The demo just has 3 fixed layers, none of them is that small. The smallest one
is 50x50.

Sure will add comment.

+      r.Inset(2, 2);
+      canvas->FillRect(r, color_, SkXfermode::kXor_Mode);
+    }
   }
   void OnDeviceScaleFactorChanged(float device_scale_factor) override {}
   void OnWindowDestroying(aura::Window* window) override {}
   void OnWindowDestroyed(aura::Window* window) override {}
   void OnWindowTargetVisibilityChanged(bool visible) override {}
   bool HasHitTestMask() const override { return false; }
   void GetHitTestMask(gfx::Path* mask) const override {}
 
  private:
   SkColor color_;
@@ skipping 103 matching lines @@
 int main(int argc, char** argv) {
   base::CommandLine::Init(argc, argv);
 
   // The exit manager is in charge of calling the dtors of singleton objects.
   base::AtExitManager exit_manager;
 
   base::i18n::InitializeICU();
 
   return DemoMain();
 }