Implements the auto-translate on click: if you have translated
a page and are navigating to a new page in the same language by
clicking a link, the new page is automatically translated.
In order to do that I moved the language state from the navigation
entry to some dedicated class that each TabContents owns.
Also added some basic unit-testing for good measure.

BUG=35477
TEST=See bug steps. Run unit-tests.
 
Review URL: http://codereview.chromium.org/596092

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@38961 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/chrome/chrome_browser.gypi b/chrome/chrome_browser.gypi
index f9a7af1..567ecc5 100755
--- a/chrome/chrome_browser.gypi
+++ b/chrome/chrome_browser.gypi
@@ -1731,6 +1731,8 @@
         'browser/tab_contents/infobar_delegate.h',
         'browser/tab_contents/interstitial_page.cc',
         'browser/tab_contents/interstitial_page.h',
+        'browser/tab_contents/language_state.h',
+        'browser/tab_contents/language_state.cc',
         'browser/tab_contents/navigation_controller.cc',
         'browser/tab_contents/navigation_controller.h',
         'browser/tab_contents/navigation_entry.cc',