Add search_terms_replacement_key field to TemplateURL.

This CL is the first step in removing the hardcoded "espv" parameter used by instant-extended to detect when to perform search term replacement in the omnibox.
The search_terms_replacement_key has beed added to prepopulated_engines, TemplateURL, policy, web_database, prefs, and sync.

BUG=161602

Review URL: https://chromiumcodereview.appspot.com/11552020

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@175014 0039d316-1c4b-4281-b951-d872f2087c98
23 files changed