Added tests to verify the effects of various methods of navigation on History

Added tests to verify the effects of various methods of navigation on History 

Also added helper functions _CheckHistory and _NavigateAndCheckHistory used by the tests below to verify that the correct changes are made to the history list. 

Tests included: 
--------------- 
testNavigateBringPageToTop: 
--- Verify that navigation brings the current page to the top of the history list. 

testReloadBringPageToTop: 
--- Verify that reloading a page brings that page to the top of the history list. 

testBackForwardBringPageToTop: 
--- Verify that back/forward brings the current page to the top of the history list. 

testAppendTabAddPage: 
--- Verify that opening a new tab adds that page to the history list. 

testOpenWindowAddPage: 
--- Verify that opening a new window to a page adds that page to the history list. 

TEST=none 
BUG=none 

Continuation of CL 7544032.

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=95569

[mberkowitz1, 2011-08-05 00:19:12]

I created a new CL under my google.com address.  Could you give it one last pass
before committing?

[dennis_jeffrey, 2011-08-05 00:29:18]

LGTM

Just 1 nit.  Feel free to go ahead and click the commit box once you address
that minor nit.  Thanks!

http://codereview.chromium.org/7574028/diff/1/history.py
File history.py (right):

http://codereview.chromium.org/7574028/diff/1/history.py#newcode254
history.py:254: index: Position of item we want to check in history list.
Remove this line.

[commit-bot: I haz the power, 2011-08-05 04:04:26]

Change committed as 95569