TaskManager: Remove some unused/unnecessary methods.

chrome/browser/task_manager/resource_provider.cc

Index: chrome/browser/task_manager/resource_provider.cc
diff --git a/chrome/browser/task_manager/resource_provider.cc b/chrome/browser/task_manager/resource_provider.cc
index 04b6bc50292c1352491ef3753c1759d6df89936e..0e59b91f05f2861c9e026868cbb4646aed1b6df6 100644
--- a/chrome/browser/task_manager/resource_provider.cc
+++ b/chrome/browser/task_manager/resource_provider.cc
@@ -44,10 +44,6 @@ size_t Resource::SqliteMemoryUsedBytes() const {
   return 0;
 }
 
-const extensions::Extension* Resource::GetExtension() const {
-  return NULL;
-}
-
 bool Resource::ReportsV8MemoryStats() const {
   return false;
 }
@@ -72,8 +68,4 @@ content::WebContents* Resource::GetWebContents() const {
   return NULL;
 }
 
-bool Resource::IsBackground() const {
-  return false;
-}
-
 }  // namespace task_manager