Only set precache.last_time when precache ran.

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

Index: chrome/android/java/src/org/chromium/chrome/browser/precache/PrecacheService.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/precache/PrecacheService.java b/chrome/android/java/src/org/chromium/chrome/browser/precache/PrecacheService.java
index 3f3c37dbfdb419be05bc7e0e0bcbfa9a901a5957..299290608bea167c43f9c2463eba705584b22414 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/precache/PrecacheService.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/precache/PrecacheService.java
@@ -72,15 +72,15 @@ public class PrecacheService extends Service {
     }
 
     @VisibleForTesting
-    void handlePrecacheCompleted() {
-        if (mIsPrecaching) finishPrecaching();
+    void handlePrecacheCompleted(boolean precacheStarted) {
+        if (mIsPrecaching) finishPrecaching(precacheStarted);
     }
 
     /** PrecacheLauncher used to run precaching. */
     private PrecacheLauncher mPrecacheLauncher = new PrecacheLauncher() {
         @Override
-        protected void onPrecacheCompleted() {
-            handlePrecacheCompleted();
+        protected void onPrecacheCompleted(boolean precacheStarted) {

[bengr, 2015/08/05 23:25:35]

Why would onPrecachCompleted be called if precacheStarted is false?

[twifkak, 2015/08/06 00:09:46]

There are two cases:
https://code.google.com/p/chromium/codesearch#chromium/src/chrome/browser/and...

This should be obvious: precache_manager is not there for some reason.

https://code.google.com/p/chromium/codesearch#chromium/src/components/precach...

The latter is a little less obvious, but you can see at line 102 that
is_precaching_ is set only if ShouldRun(). So not having sync tabs or not being
in the field trial would cause this to call onPrecacheCompleted(false).

Is it okay that this runs (and does nothing) every 15 minutes for people not in
the field trial or for people opted out of sync?

[bengr, 2015/08/07 18:41:57]

It's not ideal. What would it take to prevent it?

[twifkak, 2015/08/07 21:48:15]

Done. I renamed the parameter since it's a misnomer now.

+            handlePrecacheCompleted(precacheStarted);
         }
     };
 
@@ -161,9 +161,9 @@ public class PrecacheService extends Service {
     }
 
     /** End a precache cycle. */
-    private void finishPrecaching() {
+    private void finishPrecaching(boolean precacheStarted) {
         Log.v(TAG, "Finish precaching");
-        shutdownPrecaching();
+        shutdownPrecaching(precacheStarted);
     }
 
     /** Cancel a precache cycle. */
@@ -172,15 +172,16 @@ public class PrecacheService extends Service {
         prepareNativeLibraries();
         mPrecacheLauncher.cancel();
 
-        shutdownPrecaching();
+        shutdownPrecaching(true);
     }
 
     /**
      * Update state to indicate that precaching is no longer in progress, and stop the service.
      */
-    private void shutdownPrecaching() {
+    private void shutdownPrecaching(boolean precacheStarted) {
         mIsPrecaching = false;
         releasePrecachingWakeLock();
+        PrecacheServiceLauncher.precachingFinished(getApplicationContext(), precacheStarted);
         stopSelf();
     }