Introduce per-tab preferences service.

content/browser/tab_contents/tab_contents.cc

Index: content/browser/tab_contents/tab_contents.cc
diff --git a/content/browser/tab_contents/tab_contents.cc b/content/browser/tab_contents/tab_contents.cc
index f84158a08173fe6ef99c42117eb86eb5287d3315..dc35d2e92f7eb2a863521101c5f1b3bd9cdeca1d 100644
--- a/content/browser/tab_contents/tab_contents.cc
+++ b/content/browser/tab_contents/tab_contents.cc
@@ -13,6 +13,8 @@
 #include "base/string_util.h"
 #include "base/time.h"
 #include "base/utf_string_conversions.h"
+#include "chrome/browser/prefs/pref_service.h"
+#include "chrome/browser/profiles/profile.h"
 #include "content/browser/browser_context.h"
 #include "content/browser/child_process_security_policy.h"
 #include "content/browser/debugger/devtools_manager.h"
@@ -202,7 +204,10 @@ TabContents::TabContents(content::BrowserContext* browser_context,
           static_cast<int>(WebKit::WebView::maxTextSizeMultiplier * 100)),
       temporary_zoom_settings_(false),
       content_restrictions_(0),
-      view_type_(content::VIEW_TYPE_TAB_CONTENTS) {
+      view_type_(content::VIEW_TYPE_TAB_CONTENTS),
+      per_tab_prefs_(
+          Profile::FromBrowserContext(browser_context)->
+          GetPrefs()->CreatePrefServiceWithPerTabPrefStore()) {
 
   render_manager_.Init(browser_context, site_instance, routing_id);
 
@@ -1836,6 +1841,8 @@ WebPreferences TabContents::GetWebkitPrefs() {
   web_prefs.force_compositing_mode = true;
 #endif
 
+  // TODO: Apply overrides from per_tab_prefs_ here.
+
   return web_prefs;
 }