Add histograms to track localStorage size and load time by size.

I'm concerned that the original histograms are skewed by sample bias,
since most localStorage DBs are probably small.

Also introduce browser and renderer specific histograms. Kept the original histogram for the renderer one in order to maintain histogram data continuity.

BUG=none


Review URL: https://chromiumcodereview.appspot.com/12209085

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@181855 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 51 insertions, 1 deletions

diff --git a/webkit/dom_storage/dom_storage_area.cc b/webkit/dom_storage/dom_storage_area.cc
index d707a3a..3700238 100644
--- a/webkit/dom_storage/dom_storage_area.cc
+++ b/webkit/dom_storage/dom_storage_area.cc
@@ -7,6 +7,7 @@
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/logging.h"
+#include "base/metrics/histogram.h"
 #include "base/time.h"
 #include "third_party/WebKit/Source/Platform/chromium/public/WebString.h"
 #include "webkit/base/file_path_string_conversions.h"
@@ -277,10 +278,35 @@ void DomStorageArea::InitialImportIfNeeded() {
 
   DCHECK(backing_.get());
 
+  base::TimeTicks before = base::TimeTicks::Now();
   ValuesMap initial_values;
   backing_->ReadAllValues(&initial_values);
   map_->SwapValues(&initial_values);
   is_initial_import_done_ = true;
+  base::TimeDelta time_to_import = base::TimeTicks::Now() - before;
+  UMA_HISTOGRAM_TIMES("LocalStorage.BrowserTimeToPrimeLocalStorage",
+                      time_to_import);
+
+  size_t local_storage_size_kb = map_->bytes_used() / 1024;
+  // Track localStorage size, from 0-6MB. Note that the maximum size should be
+  // 5MB, but we add some slop since we want to make sure the max size is always
+  // above what we see in practice, since histograms can't change.
+  UMA_HISTOGRAM_CUSTOM_COUNTS("LocalStorage.BrowserLocalStorageSizeInKB",
+                              local_storage_size_kb,
+                              0, 6 * 1024, 50);
+  if (local_storage_size_kb < 100) {
+    UMA_HISTOGRAM_TIMES(
+        "LocalStorage.BrowserTimeToPrimeLocalStorageUnder100KB",
+        time_to_import);
+  } else if (local_storage_size_kb < 1000) {
+    UMA_HISTOGRAM_TIMES(
+        "LocalStorage.BrowserTimeToPrimeLocalStorage100KBTo1MB",
+        time_to_import);
+  } else {
+    UMA_HISTOGRAM_TIMES(
+        "LocalStorage.BrowserTimeToPrimeLocalStorage1MBTo5MB",
+        time_to_import);
+  }
 }
 
 DomStorageArea::CommitBatch* DomStorageArea::CreateCommitBatchIfNeeded() {
diff --git a/webkit/dom_storage/dom_storage_cached_area.cc b/webkit/dom_storage/dom_storage_cached_area.cc
index 6b20886..30d6291 100644
--- a/webkit/dom_storage/dom_storage_cached_area.cc
+++ b/webkit/dom_storage/dom_storage_cached_area.cc
@@ -154,10 +154,34 @@ void DomStorageCachedArea::Prime(int connection_id) {
       connection_id, &values,
       base::Bind(&DomStorageCachedArea::OnLoadComplete,
                  weak_factory_.GetWeakPtr()));
+  base::TimeDelta time_to_prime = base::TimeTicks::Now() - before;
+  // Keeping this histogram named the same (without the ForRenderer suffix)
+  // to maintain histogram continuity.
   UMA_HISTOGRAM_TIMES("LocalStorage.TimeToPrimeLocalStorage",
-                      base::TimeTicks::Now() - before);
+                      time_to_prime);
   map_ = new DomStorageMap(dom_storage::kPerAreaQuota);
   map_->SwapValues(&values);
+
+  size_t local_storage_size_kb = map_->bytes_used() / 1024;
+  // Track localStorage size, from 0-6MB. Note that the maximum size should be
+  // 5MB, but we add some slop since we want to make sure the max size is always
+  // above what we see in practice, since histograms can't change.
+  UMA_HISTOGRAM_CUSTOM_COUNTS("LocalStorage.RendererLocalStorageSizeInKB",
+                              local_storage_size_kb,
+                              0, 6 * 1024, 50);
+  if (local_storage_size_kb < 100) {
+    UMA_HISTOGRAM_TIMES(
+        "LocalStorage.RendererTimeToPrimeLocalStorageUnder100KB",
+        time_to_prime);
+  } else if (local_storage_size_kb < 1000) {
+    UMA_HISTOGRAM_TIMES(
+        "LocalStorage.RendererTimeToPrimeLocalStorage100KBTo1MB",
+        time_to_prime);
+  } else {
+    UMA_HISTOGRAM_TIMES(
+        "LocalStorage.RendererTimeToPrimeLocalStorage1MBTo5MB",
+        time_to_prime);
+  }
 }
 
 void DomStorageCachedArea::Reset() {