Revert "Browser: disable incognito mode"

This reverts commit 5623a091605bf1d88687dc589a61ee6b54c554fe.

 This is the 2nd commit message:

Revert "Browser: fix pie crash"

This reverts commit 06929f1b1103f5a5651a8fc71e6b6e6b10bde71d.

Change-Id: I23f2e34ee125785bba8981f0611ba4986a9beaab
(cherry picked from commit cced0d1c49130a11a2d653a361351a70d56b673a)

Conflicts:
	src/com/android/browser/PhoneUi.java
Implement client-side incognito mode

Since WebView deprecated privateBrowsing in API 17 (and killed it
for good in API 19), we were left without incognito in the Browser
app. Follow the docs' recommendations and implement it with "manual"
control of privacy-related engine options

* Internally track incognito state for tabs
* Disable all forms of storage and cache on private webviews
* Disable all cookie activity while an incognito tab is active
* Stop trying to use the deprecated "privateBrowsing" argument
  when creating webViews, always set to false

Change-Id: I23f2e34ee125635bba8981f0711ba4986a9beaab
(cherry picked from commit 1454226fc333fbabb71fc7b70de5c901df9d7019)
Show a startup page in incognito mode

Change-Id: Ib1d4be6890c81b73a46f026b6fcbb2f1e8de567d
(cherry picked from commit 8e7b2cd3a902d1bde3f389f152154cbf2d33b27c)