Produce histogram in important_file_writer code

I'm trying to ensure that prefs are being written
consistently, so this will help monitor file access
such as what is used in pref writing.

I also cleaned up the use of a histogram in pref-services.

r=rtenneti
Review URL: http://codereview.chromium.org/7890038

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@101202 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 24 insertions, 10 deletions

diff --git a/chrome/browser/prefs/pref_service.cc b/chrome/browser/prefs/pref_service.cc
index 6cb9836..1eebf82 100644
--- a/chrome/browser/prefs/pref_service.cc
+++ b/chrome/browser/prefs/pref_service.cc
@@ -102,7 +102,8 @@ class ReadErrorHandler : public PersistentPrefStore::ReadErrorDelegate {
         BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
             NewRunnableFunction(&NotifyReadError, message_id));
       }
-      UMA_HISTOGRAM_ENUMERATION("PrefService.ReadError", error, 20);
+      UMA_HISTOGRAM_ENUMERATION("PrefService.ReadError", error,
+                                PersistentPrefStore::PREF_READ_ERROR_MAX_ENUM);
     }
   }
 };
diff --git a/chrome/common/important_file_writer.cc b/chrome/common/important_file_writer.cc
index 94e7fb5..a1abd8d 100644
--- a/chrome/common/important_file_writer.cc
+++ b/chrome/common/important_file_writer.cc
@@ -12,6 +12,7 @@
 #include "base/file_util.h"
 #include "base/logging.h"
 #include "base/message_loop_proxy.h"
+#include "base/metrics/histogram.h"
 #include "base/string_number_conversions.h"
 #include "base/task.h"
 #include "base/threading/thread.h"
@@ -37,7 +38,7 @@ class WriteToDiskTask : public Task {
     // is securely created.
     FilePath tmp_file_path;
     if (!file_util::CreateTemporaryFileInDir(path_.DirName(), &tmp_file_path)) {
-      LogFailure("could not create temporary file");
+      LogFailure(FAILED_CREATING, "could not create temporary file");
       return;
     }
 
@@ -45,7 +46,7 @@ class WriteToDiskTask : public Task {
     base::PlatformFile tmp_file =
         base::CreatePlatformFile(tmp_file_path, flags, NULL, NULL);
     if (tmp_file == base::kInvalidPlatformFileValue) {
-      LogFailure("could not open temporary file");
+      LogFailure(FAILED_OPENING, "could not open temporary file");
       return;
     }
 
@@ -55,29 +56,40 @@ class WriteToDiskTask : public Task {
     base::FlushPlatformFile(tmp_file);  // Ignore return value.
 
     if (!base::ClosePlatformFile(tmp_file)) {
-      LogFailure("failed to close temporary file");
+      LogFailure(FAILED_CLOSING, "failed to close temporary file");
       file_util::Delete(tmp_file_path, false);
       return;
     }
 
     if (bytes_written < static_cast<int>(data_.length())) {
-      LogFailure("error writing, bytes_written=" +
+      LogFailure(FAILED_WRITING, "error writing, bytes_written=" +
                  base::IntToString(bytes_written));
       file_util::Delete(tmp_file_path, false);
       return;
     }
 
     if (!file_util::ReplaceFile(tmp_file_path, path_)) {
-      LogFailure("could not rename temporary file");
+      LogFailure(FAILED_RENAMING, "could not rename temporary file");
       file_util::Delete(tmp_file_path, false);
       return;
     }
   }
 
  private:
-  void LogFailure(const std::string& message) {
-    PLOG(WARNING) << "failed to write " << path_.value()
-                  << ": " << message;
+  enum TempFileFailure {
+    FAILED_CREATING,
+    FAILED_OPENING,
+    FAILED_CLOSING,
+    FAILED_WRITING,
+    FAILED_RENAMING,
+    TEMP_FILE_FAILURE_MAX
+  };
+
+  void LogFailure(TempFileFailure failure_code, const std::string& message) {
+    UMA_HISTOGRAM_ENUMERATION("ImportantFile.TempFileFailures", failure_code,
+                              TEMP_FILE_FAILURE_MAX);
+    PLOG(WARNING) << "temp file failure: " << path_.value()
+                  << " : " << message;
   }
 
   const FilePath path_;
diff --git a/chrome/common/persistent_pref_store.h b/chrome/common/persistent_pref_store.h
index b209716..b7aaf8e 100644
--- a/chrome/common/persistent_pref_store.h
+++ b/chrome/common/persistent_pref_store.h
@@ -31,7 +31,8 @@ class PersistentPrefStore : public PrefStore {
     PREF_READ_ERROR_NO_FILE,
     PREF_READ_ERROR_JSON_REPEAT,
     PREF_READ_ERROR_OTHER,
-    PREF_READ_ERROR_FILE_NOT_SPECIFIED
+    PREF_READ_ERROR_FILE_NOT_SPECIFIED,
+    PREF_READ_ERROR_MAX_ENUM
   };
 
   class ReadErrorDelegate {