Added UMA statistics logging for extensions leveldb open use.

Added leveldb usage (currently only db open) statistics reporting for
several extensions storage backends. These will be logged as:

Extensions.Database.Open.Settings
Extensions.Database.Open.State
Extensions.Database.Open.Rules

BUG=508330

Review URL: https://codereview.chromium.org/1229193002

Cr-Commit-Position: refs/heads/master@{#338596}

6 files changed, 41 insertions, 15 deletions

diff --git a/extensions/browser/value_store/leveldb_value_store.cc b/extensions/browser/value_store/leveldb_value_store.cc
index 0db63a17..39a1346 100644
--- a/extensions/browser/value_store/leveldb_value_store.cc
+++ b/extensions/browser/value_store/leveldb_value_store.cc
@@ -48,9 +48,17 @@ class ScopedSnapshot {
 
 }  // namespace
 
-LeveldbValueStore::LeveldbValueStore(const base::FilePath& db_path)
-    : db_path_(db_path) {
+LeveldbValueStore::LeveldbValueStore(const std::string& uma_client_name,
+                                     const base::FilePath& db_path)
+    : db_path_(db_path), open_histogram_(nullptr) {
   DCHECK_CURRENTLY_ON(BrowserThread::FILE);
+
+  // Used in lieu of UMA_HISTOGRAM_ENUMERATION because the histogram name is
+  // not a constant.
+  open_histogram_ = base::LinearHistogram::FactoryGet(
+      "Extensions.Database.Open." + uma_client_name, 1,
+      leveldb_env::LEVELDB_STATUS_MAX, leveldb_env::LEVELDB_STATUS_MAX + 1,
+      base::Histogram::kUmaTargetedHistogramFlag);
 }
 
 LeveldbValueStore::~LeveldbValueStore() {
@@ -331,6 +339,8 @@ scoped_ptr<ValueStore::Error> LeveldbValueStore::EnsureDbIsOpen() {
   leveldb::DB* db = NULL;
   leveldb::Status status =
       leveldb::DB::Open(options, db_path_.AsUTF8Unsafe(), &db);
+  if (open_histogram_)
+    open_histogram_->Add(leveldb_env::GetLevelDBStatusUMAValue(status));
   if (!status.ok())
     return ToValueStoreError(status, util::NoKey());
 
diff --git a/extensions/browser/value_store/leveldb_value_store.h b/extensions/browser/value_store/leveldb_value_store.h
index e94e391..2901660 100644
--- a/extensions/browser/value_store/leveldb_value_store.h
+++ b/extensions/browser/value_store/leveldb_value_store.h
@@ -14,6 +14,10 @@
 #include "extensions/browser/value_store/value_store.h"
 #include "third_party/leveldatabase/src/include/leveldb/db.h"
 
+namespace base {
+class HistogramBase;
+}  // namespace base
+
 // Value store area, backed by a leveldb database.
 // All methods must be run on the FILE thread.
 class LeveldbValueStore : public ValueStore {
@@ -24,7 +28,8 @@ class LeveldbValueStore : public ValueStore {
   // need to be notified of that, but we don't want to permanently give up.
   //
   // Must be created on the FILE thread.
-  explicit LeveldbValueStore(const base::FilePath& path);
+  LeveldbValueStore(const std::string& uma_client_name,
+                    const base::FilePath& path);
 
   // Must be deleted on the FILE thread.
   ~LeveldbValueStore() override;
@@ -91,6 +96,7 @@ class LeveldbValueStore : public ValueStore {
 
   // leveldb backend.
   scoped_ptr<leveldb::DB> db_;
+  base::HistogramBase* open_histogram_;
 
   DISALLOW_COPY_AND_ASSIGN(LeveldbValueStore);
 };
diff --git a/extensions/browser/value_store/leveldb_value_store_unittest.cc b/extensions/browser/value_store/leveldb_value_store_unittest.cc
index 3c0fd53..0604499 100644
--- a/extensions/browser/value_store/leveldb_value_store_unittest.cc
+++ b/extensions/browser/value_store/leveldb_value_store_unittest.cc
@@ -18,8 +18,10 @@
 
 namespace {
 
+const char kDatabaseUMAClientName[] = "Test";
+
 ValueStore* Param(const base::FilePath& file_path) {
-  return new LeveldbValueStore(file_path);
+  return new LeveldbValueStore(kDatabaseUMAClientName, file_path);
 }
 
 }  // namespace
@@ -48,7 +50,10 @@ class LeveldbValueStoreUnitTest : public testing::Test {
 
   void CloseStore() { store_.reset(); }
 
-  void OpenStore() { store_.reset(new LeveldbValueStore(database_path())); }
+  void OpenStore() {
+    store_.reset(
+        new LeveldbValueStore(kDatabaseUMAClientName, database_path()));
+  }
 
   LeveldbValueStore* store() { return store_.get(); }
   const base::FilePath& database_path() { return database_dir_.path(); }
diff --git a/extensions/browser/value_store/value_store_frontend.cc b/extensions/browser/value_store/value_store_frontend.cc
index 41ebf13..33cdce7 100644
--- a/extensions/browser/value_store/value_store_frontend.cc
+++ b/extensions/browser/value_store/value_store_frontend.cc
@@ -17,12 +17,12 @@ class ValueStoreFrontend::Backend : public base::RefCountedThreadSafe<Backend> {
  public:
   Backend() : storage_(NULL) {}
 
-  void Init(const base::FilePath& db_path) {
+  void Init(const std::string& uma_client_name, const base::FilePath& db_path) {
     DCHECK_CURRENTLY_ON(BrowserThread::FILE);
     DCHECK(!storage_);
     TRACE_EVENT0("ValueStoreFrontend::Backend", "Init");
     db_path_ = db_path;
-    storage_ = new LeveldbValueStore(db_path);
+    storage_ = new LeveldbValueStore(uma_client_name, db_path);
   }
 
   // This variant is useful for testing (using a mock ValueStore).
@@ -98,9 +98,10 @@ ValueStoreFrontend::ValueStoreFrontend()
     : backend_(new Backend()) {
 }
 
-ValueStoreFrontend::ValueStoreFrontend(const base::FilePath& db_path)
+ValueStoreFrontend::ValueStoreFrontend(const std::string& uma_client_name,
+                                       const base::FilePath& db_path)
     : backend_(new Backend()) {
-  Init(db_path);
+  Init(uma_client_name, db_path);
 }
 
 ValueStoreFrontend::ValueStoreFrontend(scoped_ptr<ValueStore> value_store)
@@ -114,10 +115,11 @@ ValueStoreFrontend::~ValueStoreFrontend() {
   DCHECK(CalledOnValidThread());
 }
 
-void ValueStoreFrontend::Init(const base::FilePath& db_path) {
+void ValueStoreFrontend::Init(const std::string& uma_client_name,
+                              const base::FilePath& db_path) {
   BrowserThread::PostTask(BrowserThread::FILE, FROM_HERE,
-      base::Bind(&ValueStoreFrontend::Backend::Init,
-                 backend_, db_path));
+                          base::Bind(&ValueStoreFrontend::Backend::Init,
+                                     backend_, uma_client_name, db_path));
 }
 
 void ValueStoreFrontend::Get(const std::string& key,
diff --git a/extensions/browser/value_store/value_store_frontend.h b/extensions/browser/value_store/value_store_frontend.h
index 1b93c7f..8eb1c1c 100644
--- a/extensions/browser/value_store/value_store_frontend.h
+++ b/extensions/browser/value_store/value_store_frontend.h
@@ -27,12 +27,13 @@ class ValueStoreFrontend
   typedef base::Callback<void(scoped_ptr<base::Value>)> ReadCallback;
 
   ValueStoreFrontend();
-  explicit ValueStoreFrontend(const base::FilePath& db_path);
+  ValueStoreFrontend(const std::string& uma_client_name,
+                     const base::FilePath& db_path);
   // This variant is useful for testing (using a mock ValueStore).
   explicit ValueStoreFrontend(scoped_ptr<ValueStore> value_store);
   ~ValueStoreFrontend();
 
-  void Init(const base::FilePath& db_path);
+  void Init(const std::string& uma_client_name, const base::FilePath& db_path);
 
   // Retrieves a value from the database asynchronously, passing a copy to
   // |callback| when ready. NULL is passed if no matching entry is found.
diff --git a/extensions/browser/value_store/value_store_frontend_unittest.cc b/extensions/browser/value_store/value_store_frontend_unittest.cc
index c3e6f85..be65b7b 100644
--- a/extensions/browser/value_store/value_store_frontend_unittest.cc
+++ b/extensions/browser/value_store/value_store_frontend_unittest.cc
@@ -14,6 +14,8 @@
 
 using content::BrowserThread;
 
+const char kDatabaseUMAClientName[] = "Test";
+
 class ValueStoreFrontendTest : public testing::Test {
  public:
   ValueStoreFrontendTest()
@@ -40,7 +42,7 @@ class ValueStoreFrontendTest : public testing::Test {
 
   // Reset the value store, reloading the DB from disk.
   void ResetStorage() {
-    storage_.reset(new ValueStoreFrontend(db_path_));
+    storage_.reset(new ValueStoreFrontend(kDatabaseUMAClientName, db_path_));
   }
 
   bool Get(const std::string& key, scoped_ptr<base::Value>* output) {