Makes overview center the active workspace. This avoids leaving extra

ui/aura_shell/workspace/workspace_manager.cc

 // Copyright (c) 2011 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 "ui/aura_shell/workspace/workspace_manager.h"
 
 #include <algorithm>
 
 #include "base/auto_reset.h"
 #include "ui/aura/desktop.h"
 #include "ui/aura/screen_aura.h"
@@ skipping 74 matching lines @@
 }
 
 gfx::Rect WorkspaceManager::GetDragAreaBounds() {
   return GetWorkAreaBounds(gfx::Rect(viewport_->bounds().size()));
 }
 
 void WorkspaceManager::SetOverview(bool overview) {
   if (is_overview_ == overview)
     return;
   is_overview_ = overview;
-  gfx::Rect bounds = viewport_->GetTargetBounds();
 
   ui::Transform transform;
   if (is_overview_) {
     // TODO(oshima|sky): We limit the how small windows can be shrinked
     // in overview mode, thus part of the viewport may not be visible.
     // We need to add capability to scroll/move viewport in overview mode.
     float scale = std::min(
         kMaxOverviewScale,
         workspace_size_.width() /
         static_cast<float>(viewport_->bounds().width()));
     scale = std::max(kMinOverviewScale, scale);
 
     transform.SetScale(scale, scale);
 
     int overview_width = viewport_->bounds().width() * scale;
-    int dx = overview_width < workspace_size_.width() ?
-        (workspace_size_.width() - overview_width) / 2 : 0;
+    int dx = 0;
+    if (overview_width < workspace_size_.width()) {
+      dx = (workspace_size_.width() - overview_width) / 2;
+    } else if (active_workspace_) {
+      // Center the active workspace.
+      int active_workspace_mid_x = (active_workspace_->bounds().x() +
+          active_workspace_->bounds().width() / 2) * scale;
+      dx = workspace_size_.width() / 2 - active_workspace_mid_x;
+      dx = std::min(0, std::max(dx, workspace_size_.width() - overview_width));
+    }
 
     transform.SetTranslateX(-viewport_->GetTargetBounds().x() + dx);

[oshima, 2011/10/27 08:43:05]

can you remove -viewport->GetTargetBounds().x().?  It should always  be 0 and
seems like I forgot to remove after playing with something.

     transform.SetTranslateY(workspace_size_.height() *  (1.0f - scale) / 2);
   } else {
     transform.SetTranslateX(-active_workspace_->bounds().x());
   }
 
   viewport_->layer()->SetAnimation(aura::Window::CreateDefaultAnimation());
   viewport_->layer()->SetTransform(transform);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ skipping 66 matching lines @@
   // Move to active workspace.
   if (active_workspace_) {
     ui::Transform transform;
     transform.SetTranslateX(-active_workspace_->bounds().x());
     viewport_->layer()->SetAnimation(aura::Window::CreateDefaultAnimation());
     viewport_->SetTransform(transform);
   }
 }
 
 }  // namespace aura_shell