GC triggering performance optimizations

Copy the correct starting heap size at process init.
Interfaces to set GC/managed heap parameters.

Change-Id: I0154d1523c3cfdb1214ed0315193cbb24704351f
Revert "GC triggering performance optimizations"

This reverts commit fc93169aafd63d80d62eeb783f2f17c3e326f539.
Improve scrolling cache

Scrolling cache helps make short scrolls/flings smooth but will
cause stutter when long flings are made. This patch disables
scrolling cache when long flings are made.

This patch also fixes a related bug where scrolling cache will
not be enabled properly when transitioning from flinging to scrolling.

Patch Set 2: Calculate threshold based on maximum velocity (Sang Tae Park)

Change-Id: I1fdbaad92263c9f983a32900e74eba1f0367902b
change default for unknown sources & verify apps

Change-Id: I04467c0c1ef3985b416f6e58013ddc3ce4137712