Don't set decomposed_transform_dirty_ bit dirty on appending Identity transform

cc/animation/transform_operations.cc

Index: cc/animation/transform_operations.cc
diff --git a/cc/animation/transform_operations.cc b/cc/animation/transform_operations.cc
index 970eb0dd455a7595d7e2304fec4f766f5f996293..2d99972e934c25f7c5faa004ee377d5e3818a029 100644
--- a/cc/animation/transform_operations.cc
+++ b/cc/animation/transform_operations.cc
@@ -195,7 +195,8 @@ void TransformOperations::AppendTranslate(SkMScalar 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,
@@ -210,7 +211,8 @@ void TransformOperations::AppendRotate(SkMScalar x,
   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) {
@@ -221,7 +223,8 @@ void TransformOperations::AppendScale(SkMScalar x, SkMScalar y, SkMScalar z) {
   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) {
@@ -232,7 +235,8 @@ void TransformOperations::AppendSkew(SkMScalar x, SkMScalar y) {
   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) {
@@ -241,7 +245,8 @@ void TransformOperations::AppendPerspective(SkMScalar 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) {
@@ -249,7 +254,8 @@ void TransformOperations::AppendMatrix(const gfx::Transform& matrix) {
   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() {