Allow a window to get all the way to the bottom of work area for smal…

…l windows. Previously restricted with a margin of WorkspaceWindowResizer::kMinOnscreenHeight (32) so short windows could not be dragged all the way to the bottom of the work area.

BUG=None
TEST=ash_unittests --gtest_filter=*DontDragOffBottomWithMultiDisplay*

Review URL: https://codereview.chromium.org/25005003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@225886 0039d316-1c4b-4281-b951-d872f2087c98

ash/wm/workspace/workspace_window_resizer.cc

@@ -773,8 +773,10 @@ void WorkspaceWindowResizer::AdjustBoundsForMainWindow(
       ScreenAsh::ConvertRectFromScreen(window()->parent(), display.work_area());
   if (details_.window_component == HTCAPTION) {
     // Adjust the bounds to the work area where the mouse cursor is located.
-    // Always keep kMinOnscreenHeight on the bottom.
-    int max_y = work_area.bottom() - kMinOnscreenHeight;
+    // Always keep kMinOnscreenHeight or the window height (whichever is less)
+    // on the bottom.
+    int max_y = work_area.bottom() - std::min(kMinOnscreenHeight,
+                                              bounds->height());
     if (bounds->y() > max_y) {
       bounds->set_y(max_y);
     } else if (bounds->y() <= work_area.y()) {

ash/wm/workspace/workspace_window_resizer_unittest.cc

@@ -722,6 +722,23 @@ TEST_F(WorkspaceWindowResizerTest, DontDragOffBottomWithMultiDisplay) {
   Shell::GetInstance()->display_controller()->SetLayoutForCurrentDisplays(
       ash::DisplayLayout(ash::DisplayLayout::BOTTOM, 0));
 
+  {
+    window_->SetBounds(gfx::Rect(100, 200, 300, 20));
+    DCHECK_LT(window_->bounds().height(),
+              WorkspaceWindowResizer::kMinOnscreenHeight);
+    scoped_ptr<WorkspaceWindowResizer> resizer(WorkspaceWindowResizer::Create(
+        window_.get(), gfx::Point(), HTCAPTION,
+        aura::client::WINDOW_MOVE_SOURCE_MOUSE, empty_windows()));
+    ASSERT_TRUE(resizer.get());
+    resizer->Drag(CalculateDragPoint(*resizer, 0, 400), 0);
+    int expected_y = kRootHeight - window_->bounds().height() - 10;
+    // When the mouse cursor is in the primary display, the window cannot move
+    // on non-work area but can get all the way towards the bottom,
+    // restricted only by the window height.
+    EXPECT_EQ("100," + base::IntToString(expected_y) + " 300x20",
+              window_->bounds().ToString());
+  }
+
   {
     window_->SetBounds(gfx::Rect(100, 200, 300, 400));
     scoped_ptr<WorkspaceWindowResizer> resizer(WorkspaceWindowResizer::Create(