Aura: New window shadows, desktop background debug toggle

+ Shadows support different appearances for active and inactive states.
+ Shadow opacity animates on activation change.
+ ImageGrid supports changing its images, allowing us to maintain our use of a single set of shadow layers per window.
+ Press control-alt-B in a debug build to reset the desktop background to a solid color, useful with a white background for testing shadows.
+ Window shadow art assets were added in an earlier revision.  

After this change lands I will delete the previous art assets, ui/resources/aura/shadow_rect_*

BUG=113075
TEST=aura_shell_unittests, added to ShadowControllerTest and ImageGridTest
TBR=sky@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=122547

Reverted: https://src.chromium.org/viewvc/chrome?view=rev&revision=122551

Review URL: http://codereview.chromium.org/9414028

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@122618 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 24 insertions, 11 deletions

diff --git a/ash/shell.cc b/ash/shell.cc
index 397a776..2e7630f 100644
--- a/ash/shell.cc
+++ b/ash/shell.cc
@@ -215,6 +215,7 @@ Shell::Shell(ShellDelegate* delegate)
       shelf_(NULL),
       dynamic_window_mode_(false),
       window_mode_(MODE_OVERLAPPING),
+      desktop_background_mode_(BACKGROUND_IMAGE),
       root_window_layout_(NULL),
       status_widget_(NULL) {
   // Pass ownership of the filter to the root window.
@@ -467,6 +468,27 @@ void Shell::SetWindowModeForMonitorSize(const gfx::Size& monitor_size) {
   ChangeWindowMode(new_mode);
 }
 
+void Shell::SetDesktopBackgroundMode(BackgroundMode mode) {
+  if (mode == BACKGROUND_SOLID_COLOR) {
+    // Set a solid black background.
+    // TODO(derat): Remove this in favor of having the compositor only clear the
+    // viewport when there are regions not covered by a layer:
+    // http://crbug.com/113445
+    ui::Layer* background_layer = new ui::Layer(ui::Layer::LAYER_SOLID_COLOR);
+    background_layer->SetColor(SK_ColorBLACK);
+    GetContainer(internal::kShellWindowId_DesktopBackgroundContainer)->
+        layer()->Add(background_layer);
+    root_window_layout_->SetBackgroundLayer(background_layer);
+    root_window_layout_->SetBackgroundWidget(NULL);
+  } else {
+    // Create the desktop background image.
+    root_window_layout_->SetBackgroundLayer(NULL);
+    root_window_layout_->SetBackgroundWidget(
+        internal::CreateDesktopBackground());
+  }
+  desktop_background_mode_ = mode;
+}
+
 bool Shell::IsScreenLocked() const {
   const aura::Window* lock_screen_container = GetContainer(
       internal::kShellWindowId_LockScreenContainer);
@@ -547,15 +569,7 @@ void Shell::SetupCompactWindowMode() {
   MaximizeWindows(default_container);
 
   // Set a solid black background.
-  // TODO(derat): Remove this in favor of having the compositor only clear the
-  // viewport when there are regions not covered by a layer:
-  // http://crbug.com/113445
-  ui::Layer* background_layer = new ui::Layer(ui::Layer::LAYER_SOLID_COLOR);
-  background_layer->SetColor(SK_ColorBLACK);
-  GetContainer(internal::kShellWindowId_DesktopBackgroundContainer)->
-      layer()->Add(background_layer);
-  root_window_layout_->SetBackgroundLayer(background_layer);
-  root_window_layout_->SetBackgroundWidget(NULL);
+  SetDesktopBackgroundMode(BACKGROUND_SOLID_COLOR);
 }
 
 void Shell::SetupNonCompactWindowMode() {
@@ -603,8 +617,7 @@ void Shell::SetupNonCompactWindowMode() {
   RestoreMaximizedWindows(default_container);
 
   // Create the desktop background image.
-  root_window_layout_->SetBackgroundWidget(internal::CreateDesktopBackground());
-  root_window_layout_->SetBackgroundLayer(NULL);
+  SetDesktopBackgroundMode(BACKGROUND_IMAGE);
 }
 
 void Shell::ResetLayoutManager(int container_id) {