Move CancelableTaskTracker to //base/task/CancelableTaskTracker.

CancelableTaskTracker is used by //chrome code that is due to componentized.
This CL moves the class to //base/task and wraps it in the ::base::task namespace.

BUG=335135
TBR=thakis

Review URL: https://codereview.chromium.org/137263007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249397 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/chrome/browser/icon_manager.h b/chrome/browser/icon_manager.h
index dafd147..ad10d73 100644
--- a/chrome/browser/icon_manager.h
+++ b/chrome/browser/icon_manager.h
@@ -48,8 +48,8 @@
 #include <map>
 
 #include "base/files/file_path.h"
+#include "base/task/cancelable_task_tracker.h"
 #include "chrome/browser/icon_loader.h"
-#include "chrome/common/cancelable_task_tracker.h"
 #include "ui/gfx/image/image.h"
 
 class IconManager : public IconLoader::Delegate {
@@ -77,10 +77,11 @@
   //    should never keep it or delete it.
   // 3. The gfx::Image pointer passed to the callback may be NULL if decoding
   //    failed.
-  CancelableTaskTracker::TaskId LoadIcon(const base::FilePath& file_name,
-                                         IconLoader::IconSize size,
-                                         const IconRequestCallback& callback,
-                                         CancelableTaskTracker* tracker);
+  base::CancelableTaskTracker::TaskId LoadIcon(
+      const base::FilePath& file_name,
+      IconLoader::IconSize size,
+      const IconRequestCallback& callback,
+      base::CancelableTaskTracker* tracker);
 
   // IconLoader::Delegate interface.
   virtual bool OnGroupLoaded(IconLoader* loader,