Fix top K percentage computation when loading profile data.
Fix top K percentage computation when loading profile data.

Don't count boot and null methods when computing top K percentage for
sampled methods.

Bug: 15462067
Bug: 12877748
Change-Id: I11c2ea541066a15bc8a5ad323e21ccbfdf81c2c5

treadstoneproject/artinst,treadstoneproject/artinst,treadstoneproject/artinst,treadstoneproject/artinst,treadstoneproject/artinst