WebViewCore: Fix the issue of wrong zoom density when opening web pages with overview mode disabled.

On JellyBean browser, when pages opened
 with "open pages in overview" disabled and "Default zoom" option set to
 "Far" or "Close", the zoom density is not correct.

 The issue is caused by the wrong scale factor calculated when setup
 viewport. it is fixed to 1.5 in JB. whereas it should be different for
 different "Default zoom" setting.

 This Patch will fix this issue. it set the scale factor to the
 defaultzoomscale calculated considering zoom density. it also add
 adjust process to guarantee the zoom density is right after navigating
 page with specified viewport "target-densitydpi".

 Author: Zang Lin <lin.zang@intel.com>
 Signed-off-by: Jack Ren <jack.ren@intel.com>
 Signed-off-by: Bruce Beare <bruce.j.beare@intel.com>

Change-Id: I68dd193457c40ce9eb73635297ce7bb61b373bac
Fixes for clang:
PackageInfo is a class, not a struct.
String16 is contained in the android namespace. Do not namespace prefix it
within the android namespace.
Explicitly specify which std classes are necessary to prevent ambiguous
type errors. (map, set)

Change-Id: I0d01477a976e770821ebae8847f8d11b132a15d6
Use scaled font size for no recent apps text

Change-Id: Ib200928db09bcdd6661de5e450e2fc9c1b5566cf
GC triggering performance optimizations

Credits to team CM.

Change-Id: Id491a095f2faaf1e05fb44525063254bcff0a2bc
Treat default value that wasn't found as empty value.

Fixes http://code.google.com/p/android/issues/detail?id=33220

Change-Id: If22e8b245f688d922c168aa54c8acf743c0644d7