browser: allow to load browser internal assets

The new webview classes avoid to load urls from local file schemes. Just replace the load of internal browser assets (most_visited) from loadUrl to loadData.

Change-Id: Iee633a1a3599a7e752e15452fa04e15baac2e256
JIRA: CYAN-3564
Issue: https://jira.cyanogenmod.org/browse/CYAN-3564
Signed-off-by: Jorge Ruesga <jorge@ruesga.com>
Reimplement titlebar autohiding to be compatible with chromium webview.

Patch Set 4: Fix code formatting

Change-Id: I4de873f7c089d4f7dede944d05f48d03000f3d99
BrowserSettings: update desktop UA string to match Chrome 30

Now that we're using a Chromium-based WebView which closely matches
Chrome 30, we should report as a newer Chrome version when masquerading
as a desktop browser.

Change-Id: I301a8cfac9a83e66a6749872943e80ff5c4740a1
Replace removed NARROW_COLUMNS layout mode with TEXT_AUTOSIZING

For reasons which I completely fail to understand, Google elected not to
implement the very useful NARROW_COLUMNS layout mode (double-tap to
reflow text) in Chromium WebView, and instead chose to implement
TEXT_AUTOSIZING (buggy heuristic-based font inflation).  But complaining
isn't going to get it back, and font inflation is better than nothing on
small screens, so replace NARROW_COLUMNS with TEXT_AUTOSIZING to restore
some support for resizing text to be legible on screen.

Change-Id: Ieeb03d38e8a7386e8e8f811c570aa17bfabf4337
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