When mLastComputedTaskSize is empty we will recalculate and set it before...

When mLastComputedTaskSize is empty we will recalculate and set it before determining scale and pivot

Bug: 326550571

Test: manually set computed task size to 0 simulating unset circumstance, and ran logs verifying infinite, added fix, and verified logs showing the same scale before and after with get tasksize set

Flag: none
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:fca7ee23ba35c35292e6f26ca051cd64c437ca27)
Merged-In: I0f928885e2fc6cfc0d6a064d6e9f1c614bf7a5af
Change-Id: I0f928885e2fc6cfc0d6a064d6e9f1c614bf7a5af