Polish the result communication and display of the browsing data counters.

chrome/browser/browsing_data/cache_counter_browsertest.cc

Index: chrome/browser/browsing_data/cache_counter_browsertest.cc
diff --git a/chrome/browser/browsing_data/cache_counter_browsertest.cc b/chrome/browser/browsing_data/cache_counter_browsertest.cc
index a156c73d7aa58edb5ac041bd1a823334a31a88cc..cc081a7f662b6f41891e992ec0597f2aa0741c56 100644
--- a/chrome/browser/browsing_data/cache_counter_browsertest.cc
+++ b/chrome/browser/browsing_data/cache_counter_browsertest.cc
@@ -129,11 +129,13 @@ class CacheCounterTest : public InProcessBrowserTest {
   }
 
   // Callback from the counter.
-  void CountingCallback(bool finished, BrowsingDataCounter::ResultInt count) {
+  void CountingCallback(scoped_ptr<BrowsingDataCounter::Result> result) {
     DCHECK_CURRENTLY_ON(BrowserThread::UI);
-    finished_ = finished;
-    result_ = count;
-    if (run_loop_ && finished)
+
+    finished_ = result->Finished();
+    result_ = result->Value();

[Bernhard Bauer, 2015/11/03 11:37:02]

...aand this would crash now, no?

[msramek, 2015/11/03 11:57:06]

Hm :/ If I need to guard access to Value() with Finished(), it's not that much
different than as if I had to also cast to FinishedResult.

My preference would be to keep it simple and and just remove NOTREACHED, since
unfinished computation implies that the result value cannot be relied on.
Currently, it's up to the UI layer to understand and interpret that.

The other option is to actually move Value() to FinishedResult. It will be
cleaner, but more code on the callsites.

[Bernhard Bauer, 2015/11/03 12:07:08]

Or store the result instead of the two values.

[msramek, 2015/11/03 13:15:39]

If I store it as a Result, I'll still have to do the conversion in GetResult()
and DCHECKs. So it should be converted here when we get the callback anyway. So
I did that, and I left the members stored separately.

In clear_browser_data_handler.cc, I just inlined the two casts, as I find that
more readable than nesting the whole "if (Finished())" branch one level deeper.

+
+    if (run_loop_ && finished_)
       run_loop_->Quit();
   }