[Downloads] Some UMA for downloads resumption.

* Count number of requests initiated due to resumption.

* Count downloads that have a strong validator and supports range
  requests, since those are candidates for partial resumption.

* Count downloads that are interrupted after the associated WebContents
  is destroyed.

BUG=7648

Review URL: https://chromiumcodereview.appspot.com/20609004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@214461 0039d316-1c4b-4281-b951-d872f2087c98

7 files changed, 34 insertions, 8 deletions

diff --git a/content/browser/download/download_item_impl.cc b/content/browser/download/download_item_impl.cc
index b49a256..e54ab9e 100644
--- a/content/browser/download/download_item_impl.cc
+++ b/content/browser/download/download_item_impl.cc
@@ -1398,6 +1398,8 @@ void DownloadItemImpl::Interrupt(DownloadInterruptReason reason) {
 
   TransitionTo(INTERRUPTED_INTERNAL, DONT_UPDATE_OBSERVERS);
   RecordDownloadInterrupted(reason, received_bytes_, total_bytes_);
+  if (!GetWebContents())
+    RecordDownloadCount(INTERRUPTED_WITHOUT_WEBCONTENTS);
 
   AutoResumeIfValid();
   UpdateObservers();
diff --git a/content/browser/download/download_item_impl_unittest.cc b/content/browser/download/download_item_impl_unittest.cc
index 7d34837..ff5d326 100644
--- a/content/browser/download/download_item_impl_unittest.cc
+++ b/content/browser/download/download_item_impl_unittest.cc
@@ -496,7 +496,7 @@ TEST_F(DownloadItemTest, LimitRestartsAfterInterrupted) {
     // to be callled, so we simply verify that GetWebContents() is called.
     if (i < (DownloadItemImpl::kMaxAutoResumeAttempts - 1)) {
       EXPECT_CALL(*mock_request_handle, GetWebContents())
-          .WillOnce(Return(static_cast<WebContents*>(NULL)));
+          .WillRepeatedly(Return(static_cast<WebContents*>(NULL)));
     }
 
     // Copied key parts of DoIntermediateRename & AddDownloadFileToDownloadItem
diff --git a/content/browser/download/download_manager_impl.cc b/content/browser/download/download_manager_impl.cc
index 47e3aaa..58fe952 100644
--- a/content/browser/download/download_manager_impl.cc
+++ b/content/browser/download/download_manager_impl.cc
@@ -524,6 +524,7 @@ void DownloadManagerImpl::OnSavePackageSuccessfullyFinished(
 void DownloadManagerImpl::ResumeInterruptedDownload(
     scoped_ptr<content::DownloadUrlParameters> params,
     uint32 id) {
+  RecordDownloadSource(INITIATED_BY_RESUMPTION);
   BrowserThread::PostTask(
       BrowserThread::IO,
       FROM_HERE,
diff --git a/content/browser/download/download_resource_handler.cc b/content/browser/download/download_resource_handler.cc
index 2a02cf9..3b4844e 100644
--- a/content/browser/download/download_resource_handler.cc
+++ b/content/browser/download/download_resource_handler.cc
@@ -171,11 +171,10 @@ bool DownloadResourceHandler::OnResponseStarted(
   const net::HttpResponseHeaders* headers = request_->response_headers();
   if (headers) {
     std::string last_modified_hdr;
-    std::string etag;
     if (headers->EnumerateHeader(NULL, "Last-Modified", &last_modified_hdr))
       info->last_modified = last_modified_hdr;
-    if (headers->EnumerateHeader(NULL, "ETag", &etag))
-      info->etag = etag;
+    if (headers->EnumerateHeader(NULL, "ETag", &etag_))
+      info->etag = etag_;
 
     int status = headers->response_code();
     if (2 == status / 100  && status != net::HTTP_PARTIAL_CONTENT) {
@@ -373,7 +372,7 @@ bool DownloadResourceHandler::OnResponseCompleted(
     }
   }
 
-  RecordAcceptsRanges(accept_ranges_, bytes_read_);
+  RecordAcceptsRanges(accept_ranges_, bytes_read_, etag_);
   RecordNetworkBlockage(
       base::TimeTicks::Now() - download_start_time_, total_pause_time_);
 
diff --git a/content/browser/download/download_resource_handler.h b/content/browser/download/download_resource_handler.h
index 866bffb..d38068d 100644
--- a/content/browser/download/download_resource_handler.h
+++ b/content/browser/download/download_resource_handler.h
@@ -126,6 +126,7 @@ class CONTENT_EXPORT DownloadResourceHandler
   size_t last_buffer_size_;
   int64 bytes_read_;
   std::string accept_ranges_;
+  std::string etag_;
 
   int pause_count_;
   bool was_deferred_;
diff --git a/content/browser/download/download_stats.cc b/content/browser/download/download_stats.cc
index c1b251d..f8a1e09 100644
--- a/content/browser/download/download_stats.cc
+++ b/content/browser/download/download_stats.cc
@@ -179,7 +179,8 @@ void RecordDownloadWriteLoopCount(int count) {
 }
 
 void RecordAcceptsRanges(const std::string& accepts_ranges,
-                         int64 download_len) {
+                         int64 download_len,
+                         const std::string& etag) {
   int64 max = 1024 * 1024 * 1024;  // One Terabyte.
   download_len /= 1024;  // In Kilobytes
   static const int kBuckets = 50;
@@ -196,6 +197,10 @@ void RecordAcceptsRanges(const std::string& accepts_ranges,
                                 1,
                                 max,
                                 kBuckets);
+    // ETags that start with "W/" are considered weak ETags which don't imply
+    // byte-wise equality.
+    if (!StartsWithASCII(etag, "w/", false))
+      RecordDownloadCount(STRONG_ETAG_AND_ACCEPTS_RANGES);
   } else {
     UMA_HISTOGRAM_CUSTOM_COUNTS("Download.AcceptRangesMissingOrInvalid.KBytes",
                                 download_len,
diff --git a/content/browser/download/download_stats.h b/content/browser/download/download_stats.h
index 287b34d..be2ae4b 100644
--- a/content/browser/download/download_stats.h
+++ b/content/browser/download/download_stats.h
@@ -68,6 +68,14 @@ enum DownloadCountTypes {
   // successful invocation of ScanAndSaveDownloadedFile().
   FILE_MISSING_AFTER_SUCCESSFUL_SCAN_COUNT,
 
+  // Count of downloads that supplies a strong ETag and has a 'Accept-Ranges:
+  // bytes' header. These downloads are candidates for partial resumption.
+  STRONG_ETAG_AND_ACCEPTS_RANGES,
+
+  // Count of downloads that didn't have a valid WebContents at the time it was
+  // interrupted.
+  INTERRUPTED_WITHOUT_WEBCONTENTS,
+
   DOWNLOAD_COUNT_TYPES_LAST_ENTRY
 };
 
@@ -85,6 +93,13 @@ enum DownloadSource {
   // (e.g. by Alt-click) through the IPC ViewHostMsg_DownloadUrl.
   INITIATED_BY_RENDERER,
 
+  // Fomerly INITIATED_BY_PEPPER_SAVE.
+  DOWNLOAD_SOURCE_UNUSED_3,
+
+  // A request that was initiated as a result of resuming an interrupted
+  // download.
+  INITIATED_BY_RESUMPTION,
+
   DOWNLOAD_SOURCE_LAST_ENTRY
 };
 
@@ -141,8 +156,11 @@ void RecordBandwidth(double actual_bandwidth, double potential_bandwidth);
 // download completed.
 void RecordOpen(const base::Time& end, bool first);
 
-// Record whether or not the server accepts ranges, and the download size.
-void RecordAcceptsRanges(const std::string& accepts_ranges, int64 download_len);
+// Record whether or not the server accepts ranges, and the download size. Also
+// counts if a strong ETag is supplied. The combination of range request support
+// and ETag indicates downloads that are candidates for partial resumption.
+void RecordAcceptsRanges(const std::string& accepts_ranges, int64 download_len,
+                         const std::string& etag);
 
 // Record the number of downloads removed by ClearAll.
 void RecordClearAllSize(int size);