Don't set decomposed_transform_dirty_ bit dirty on appending Identity transform

cc/animation/transform_operations.cc

 // Copyright 2013 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 "cc/animation/transform_operations.h"
 
 #include <algorithm>
 
 #include "ui/gfx/animation/tween.h"
 #include "ui/gfx/geometry/box_f.h"
@@ skipping 177 matching lines @@
 void TransformOperations::AppendTranslate(SkMScalar x,
                                           SkMScalar y,
                                           SkMScalar z) {
   TransformOperation to_add;
   to_add.matrix.Translate3d(x, y, z);
   to_add.type = TransformOperation::TRANSFORM_OPERATION_TRANSLATE;
   to_add.translate.x = x;
   to_add.translate.y = y;
   to_add.translate.z = z;
   operations_.push_back(to_add);
-  decomposed_transform_dirty_ = true;
+  if (!to_add.IsIdentity())
+    decomposed_transform_dirty_ = true;
 }
 
 void TransformOperations::AppendRotate(SkMScalar x,
                                        SkMScalar y,
                                        SkMScalar z,
                                        SkMScalar degrees) {
   TransformOperation to_add;
   to_add.matrix.RotateAbout(gfx::Vector3dF(x, y, z), degrees);
   to_add.type = TransformOperation::TRANSFORM_OPERATION_ROTATE;
   to_add.rotate.axis.x = x;
   to_add.rotate.axis.y = y;
   to_add.rotate.axis.z = z;
   to_add.rotate.angle = degrees;
   operations_.push_back(to_add);
-  decomposed_transform_dirty_ = true;
+  if (!to_add.IsIdentity())
+    decomposed_transform_dirty_ = true;
 }
 
 void TransformOperations::AppendScale(SkMScalar x, SkMScalar y, SkMScalar z) {
   TransformOperation to_add;
   to_add.matrix.Scale3d(x, y, z);
   to_add.type = TransformOperation::TRANSFORM_OPERATION_SCALE;
   to_add.scale.x = x;
   to_add.scale.y = y;
   to_add.scale.z = z;
   operations_.push_back(to_add);
-  decomposed_transform_dirty_ = true;
+  if (!to_add.IsIdentity())
+    decomposed_transform_dirty_ = true;
 }
 
 void TransformOperations::AppendSkew(SkMScalar x, SkMScalar y) {
   TransformOperation to_add;
   to_add.matrix.SkewX(x);
   to_add.matrix.SkewY(y);
   to_add.type = TransformOperation::TRANSFORM_OPERATION_SKEW;
   to_add.skew.x = x;
   to_add.skew.y = y;
   operations_.push_back(to_add);
-  decomposed_transform_dirty_ = true;
+  if (!to_add.IsIdentity())
+    decomposed_transform_dirty_ = true;
 }
 
 void TransformOperations::AppendPerspective(SkMScalar depth) {
   TransformOperation to_add;
   to_add.matrix.ApplyPerspectiveDepth(depth);
   to_add.type = TransformOperation::TRANSFORM_OPERATION_PERSPECTIVE;
   to_add.perspective_depth = depth;
   operations_.push_back(to_add);
-  decomposed_transform_dirty_ = true;
+  if (!to_add.IsIdentity())
+    decomposed_transform_dirty_ = true;
 }
 
 void TransformOperations::AppendMatrix(const gfx::Transform& matrix) {
   TransformOperation to_add;
   to_add.matrix = matrix;
   to_add.type = TransformOperation::TRANSFORM_OPERATION_MATRIX;
   operations_.push_back(to_add);
-  decomposed_transform_dirty_ = true;
+  if (!to_add.IsIdentity())
+    decomposed_transform_dirty_ = true;
 }
 
 void TransformOperations::AppendIdentity() {
   operations_.push_back(TransformOperation());
 }
 
 bool TransformOperations::IsIdentity() const {
   for (size_t i = 0; i < operations_.size(); ++i) {
     if (!operations_[i].IsIdentity())
       return false;
@@ skipping 46 matching lines @@
       decomposed_transform_.reset(new gfx::DecomposedTransform());
     gfx::Transform transform = Apply();
     if (!gfx::DecomposeTransform(decomposed_transform_.get(), transform))
       return false;
     decomposed_transform_dirty_ = false;
   }
   return true;
 }
 
 }  // namespace cc