Automatically adapt to faster/slower uploads of renderer histograms

This replaces the current time based approach (chrome is given N seconds
to upload all renederer histograms) with an asynch callback approach
that waits until all renderers have responded (with their updates). It
uses a fall-back timer to ensure that a hung renderer won't delay things
forever as well.

This causes faster (and complete) updates in about:histograms as well
as generally assuring complete updates during UMA gatherings.

This code was contributed by Raman Tenneti in CL 42496
http://codereview.chromium.org/42496

bug=12850

r=raman
Review URL: http://codereview.chromium.org/113473

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@17123 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 8 insertions, 8 deletions

diff --git a/chrome/renderer/renderer_histogram_snapshots.cc b/chrome/renderer/renderer_histogram_snapshots.cc
index 6d0507d..025eb73 100644
--- a/chrome/renderer/renderer_histogram_snapshots.cc
+++ b/chrome/renderer/renderer_histogram_snapshots.cc
@@ -22,13 +22,13 @@ RendererHistogramSnapshots::RendererHistogramSnapshots()
 }
 
 // Send data quickly!
-void RendererHistogramSnapshots::SendHistograms() {
+void RendererHistogramSnapshots::SendHistograms(int sequence_number) {
   RenderThread::current()->message_loop()->PostTask(FROM_HERE,
       renderer_histogram_snapshots_factory_.NewRunnableMethod(
-          &RendererHistogramSnapshots::UploadAllHistrograms));
+          &RendererHistogramSnapshots::UploadAllHistrograms, sequence_number));
 }
 
-void RendererHistogramSnapshots::UploadAllHistrograms() {
+void RendererHistogramSnapshots::UploadAllHistrograms(int sequence_number) {
   StatisticsRecorder::Histograms histograms;
   StatisticsRecorder::GetHistograms(&histograms);
 
@@ -39,11 +39,11 @@ void RendererHistogramSnapshots::UploadAllHistrograms() {
        it++) {
     UploadHistrogram(**it, &pickled_histograms);
   }
-  // Send the handle over synchronous IPC.
-  if (pickled_histograms.size() > 0) {
-    RenderThread::current()->Send(
-        new ViewHostMsg_RendererHistograms(pickled_histograms));
-  }
+  // Send the sequence number and list of pickled histograms over synchronous
+  // IPC.
+  RenderThread::current()->Send(
+      new ViewHostMsg_RendererHistograms(
+          sequence_number, pickled_histograms));
 }
 
 // Extract snapshot data and then send it off the the Browser process