cros: Fix crash with screen rotation animation

Ensure the interpolated_transform_ member is initialized in the constructor
such that OnGetTarget() can be called before OnStart().  I added the animation
delegate to the constructor as we need it to initialize the transformation
matrix.

BUG=172328
TEST=manual, Ctrl-Alt-Shift-F3 should spin the windows and not crash


Review URL: https://chromiumcodereview.appspot.com/12087009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@179082 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 18 insertions, 7 deletions

diff --git a/ash/rotator/screen_rotation.cc b/ash/rotator/screen_rotation.cc
index d4330a4..ecb45ef 100644
--- a/ash/rotator/screen_rotation.cc
+++ b/ash/rotator/screen_rotation.cc
@@ -31,19 +31,24 @@ base::TimeDelta GetTransitionDuration(int degrees) {
 
 }  // namespace
 
-ScreenRotation::ScreenRotation(int degrees)
+ScreenRotation::ScreenRotation(int degrees,
+                               ui::LayerAnimationDelegate* delegate)
     : ui::LayerAnimationElement(GetProperties(),
                                 GetTransitionDuration(degrees)),
       degrees_(degrees) {
+  InitTransform(delegate);
 }
 
 ScreenRotation::~ScreenRotation() {
 }
 
-void ScreenRotation::OnStart(ui::LayerAnimationDelegate* delegate) {
-  // No rotation required.
-  if (degrees_ == 0)
+void ScreenRotation::InitTransform(ui::LayerAnimationDelegate* delegate) {
+  // No rotation required, use the identity transform.
+  if (degrees_ == 0) {
+    interpolated_transform_.reset(
+        new ui::InterpolatedConstantTransform(gfx::Transform()));
     return;
+  }
 
   const gfx::Transform& current_transform =
       delegate->GetTransformForAnimation();
@@ -101,6 +106,9 @@ void ScreenRotation::OnStart(ui::LayerAnimationDelegate* delegate) {
   interpolated_transform_->SetChild(rotation.release());
 }
 
+void ScreenRotation::OnStart(ui::LayerAnimationDelegate* delegate) {
+}
+
 bool ScreenRotation::OnProgress(double t,
                                 ui::LayerAnimationDelegate* delegate) {
   delegate->SetTransformFromAnimation(interpolated_transform_->Interpolate(t));
diff --git a/ash/rotator/screen_rotation.h b/ash/rotator/screen_rotation.h
index 88bad2b..83d696c 100644
--- a/ash/rotator/screen_rotation.h
+++ b/ash/rotator/screen_rotation.h
@@ -32,10 +32,15 @@ class ASH_EXPORT ScreenRotation : public ui::LayerAnimationElement {
  public:
   // The screen rotation does not own the view or the listener, and these
   // objects are required to outlive the Screen rotation object.
-  ScreenRotation(int degrees);
+  // |delegate| is usually a layer.
+  ScreenRotation(int degrees, ui::LayerAnimationDelegate* delegate);
   virtual ~ScreenRotation();
 
  private:
+  // Generates the intermediate transformation matrices used during the
+  // animation.
+  void InitTransform(ui::LayerAnimationDelegate* delegate);
+
   // Implementation of ui::LayerAnimationDelegate
   virtual void OnStart(ui::LayerAnimationDelegate* delegate) OVERRIDE;
   virtual bool OnProgress(double t,
@@ -46,8 +51,6 @@ class ASH_EXPORT ScreenRotation : public ui::LayerAnimationElement {
   static const ui::LayerAnimationElement::AnimatableProperties&
       GetProperties();
 
-  // Generates the intermediate transformation matrices used during the
-  // animation.
   scoped_ptr<ui::InterpolatedTransform> interpolated_transform_;
 
   // The number of degrees to rotate.