Revert of PrecacheFetcher::CancelPrecaching should run in the main UI thread

chrome/android/java/src/org/chromium/chrome/browser/precache/PrecacheController.java

Index: chrome/android/java/src/org/chromium/chrome/browser/precache/PrecacheController.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/precache/PrecacheController.java b/chrome/android/java/src/org/chromium/chrome/browser/precache/PrecacheController.java
index 28badf446635bb5dfe145ee2e7a4ac63ba6e18f9..4ee943e13f58bed495e048134c90bffab5038e92 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/precache/PrecacheController.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/precache/PrecacheController.java
@@ -21,7 +21,6 @@
 
 import org.chromium.base.ContextUtils;
 import org.chromium.base.Log;
-import org.chromium.base.ThreadUtils;
 import org.chromium.base.VisibleForTesting;
 import org.chromium.base.library_loader.LibraryLoader;
 import org.chromium.base.metrics.RecordHistogram;
@@ -414,20 +413,13 @@
      * Cancels the current precache session.
      * @param event the failure reason.
      */
-    private void cancelPrecaching(final int event) {
-        // cancelPrecaching() could be called from PrecacheManager::Shutdown(), precache GCM task,
-        // etc., where it could be a different thread.
-        ThreadUtils.runOnUiThread(new Runnable() {
-            @Override
-            public void run() {
-                Log.v(TAG, "canceling precache session");
-                if (setIsPrecaching(false)) {
-                    mPrecacheLauncher.cancel();
-                    shutdownPrecaching(true);
-                }
-                PrecacheUMA.record(event);
-            }
-        });
+    private void cancelPrecaching(int event) {
+        Log.v(TAG, "canceling precache session");
+        if (setIsPrecaching(false)) {
+            mPrecacheLauncher.cancel();
+            shutdownPrecaching(true);
+        }
+        PrecacheUMA.record(event);
     }
 
     /**