Why is that error showing in Unity Editor.. Is that Unity's fault or Qualcomm?
Assets/Qualcomm Augmented Reality/Scripts/TrackerScript.cs(231,12): error CS0117: `UnityEngine.GL' does not contain a definition for`InvalidateState'
I made refactoring/renaming function called “Clear” to “DeActivate” and got same error ! but insted of “InvalidateState” I got “Assets/Qualcomm Augmented Reality/Scripts/TrackerScript.cs(231,12): error CS0117: UnityEngine.GL’ does not contain a definition for DeActivate’”
Check your code for other “Clear” to “InvalidateState” once 
It is likely that this TrackerScript is not up to date so that it can work with Unity 3.0 (or was maybe broken beforehand?). I've not seen this script nor did I study in-depth Unity 2.6's GL interface, but as it stands, UnityEngine.GL does not contain a definition for anything called forInvalidateState. See for yourself.
If you are trying to ascribe blame, it would be with Qualcomm as Unity was updated and Qualcomm did not update their scripts when Unity updated their code (or Qualcomm wrote an erroneous script in the first place?). Your options are to wait for Qualcomm to correct the error (assuming that they are aware of it and intend to see it resolved), fix the error yourself or try to find and roll-back to a version of Unity in which their code worked.