Add experiment to measure time to hash extension content as we read it

This required adding 2 new methods to URLRequestFileJob to let
subclasses get notified when seeks and reads complete, so that our
URLRequestExtensionJob class is able to compute the hash of the content
read and know what bytes from the file those correspond to (e.g. if there
was a Range specified and we didn't read all the bytes).

BUG=360909

Review URL: https://codereview.chromium.org/227943003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@263571 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 72 insertions, 13 deletions

diff --git a/extensions/browser/extension_protocols.cc b/extensions/browser/extension_protocols.cc
index 681a85f..53315cb 100644
--- a/extensions/browser/extension_protocols.cc
+++ b/extensions/browser/extension_protocols.cc
@@ -5,6 +5,8 @@
 #include "extensions/browser/extension_protocols.h"
 
 #include <algorithm>
+#include <string>
+#include <vector>
 
 #include "base/base64.h"
 #include "base/compiler_specific.h"
@@ -14,9 +16,12 @@
 #include "base/logging.h"
 #include "base/memory/weak_ptr.h"
 #include "base/message_loop/message_loop.h"
+#include "base/metrics/field_trial.h"
 #include "base/metrics/histogram.h"
 #include "base/path_service.h"
 #include "base/sha1.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/threading/sequenced_worker_pool.h"
@@ -25,6 +30,8 @@
 #include "build/build_config.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/resource_request_info.h"
+#include "crypto/secure_hash.h"
+#include "crypto/sha2.h"
 #include "extensions/browser/extensions_browser_client.h"
 #include "extensions/browser/info_map.h"
 #include "extensions/common/constants.h"
@@ -37,6 +44,7 @@
 #include "extensions/common/manifest_handlers/incognito_info.h"
 #include "extensions/common/manifest_handlers/shared_module_info.h"
 #include "extensions/common/manifest_handlers/web_accessible_resources_info.h"
+#include "net/base/io_buffer.h"
 #include "net/base/net_errors.h"
 #include "net/http/http_request_headers.h"
 #include "net/http/http_response_headers.h"
@@ -157,20 +165,31 @@ class URLRequestExtensionJob : public net::URLRequestFileJob {
                          const std::string& content_security_policy,
                          bool send_cors_header,
                          bool follow_symlinks_anywhere)
-    : net::URLRequestFileJob(
-          request, network_delegate, base::FilePath(),
-          BrowserThread::GetBlockingPool()->GetTaskRunnerWithShutdownBehavior(
-                  base::SequencedWorkerPool::SKIP_ON_SHUTDOWN)),
-      directory_path_(directory_path),
-      // TODO(tc): Move all of these files into resources.pak so we don't break
-      // when updating on Linux.
-      resource_(extension_id, directory_path, relative_path),
-      content_security_policy_(content_security_policy),
-      send_cors_header_(send_cors_header),
-      weak_factory_(this) {
+      : net::URLRequestFileJob(
+            request,
+            network_delegate,
+            base::FilePath(),
+            BrowserThread::GetBlockingPool()->GetTaskRunnerWithShutdownBehavior(
+                base::SequencedWorkerPool::SKIP_ON_SHUTDOWN)),
+        seek_position_(0),
+        bytes_read_(0),
+        directory_path_(directory_path),
+        // TODO(tc): Move all of these files into resources.pak so we don't
+        // break when updating on Linux.
+        resource_(extension_id, directory_path, relative_path),
+        content_security_policy_(content_security_policy),
+        send_cors_header_(send_cors_header),
+        weak_factory_(this) {
     if (follow_symlinks_anywhere) {
       resource_.set_follow_symlinks_anywhere();
     }
+    const std::string& group =
+        base::FieldTrialList::FindFullName("ExtensionContentHashMeasurement");
+    if (group == "Yes") {
+      base::ElapsedTimer timer;
+      hash_.reset(crypto::SecureHash::Create(crypto::SecureHash::SHA256));
+      hashing_time_ = timer.Elapsed();
+    }
   }
 
   virtual void GetResponseInfo(net::HttpResponseInfo* info) OVERRIDE {
@@ -182,7 +201,8 @@ class URLRequestExtensionJob : public net::URLRequestFileJob {
     base::Time* last_modified_time = new base::Time();
     bool posted = BrowserThread::PostBlockingPoolTaskAndReply(
         FROM_HERE,
-        base::Bind(&ReadResourceFilePathAndLastModifiedTime, resource_,
+        base::Bind(&ReadResourceFilePathAndLastModifiedTime,
+                   resource_,
                    directory_path_,
                    base::Unretained(read_file_path),
                    base::Unretained(last_modified_time)),
@@ -193,8 +213,35 @@ class URLRequestExtensionJob : public net::URLRequestFileJob {
     DCHECK(posted);
   }
 
+  virtual void OnSeekComplete(int64 result) OVERRIDE {
+    DCHECK_EQ(seek_position_, 0);
+    seek_position_ = result;
+  }
+
+  virtual void OnReadComplete(net::IOBuffer* buffer, int result) OVERRIDE {
+    UMA_HISTOGRAM_COUNTS("ExtensionUrlRequest.OnReadCompleteResult", result);
+    if (result > 0) {
+      bytes_read_ += result;
+      if (hash_.get()) {
+        base::ElapsedTimer timer;
+        hash_->Update(buffer->data(), result);
+        hashing_time_ += timer.Elapsed();
+      }
+    }
+  }
+
  private:
-  virtual ~URLRequestExtensionJob() {}
+  virtual ~URLRequestExtensionJob() {
+    if (hash_.get()) {
+      base::ElapsedTimer timer;
+      std::string hash_bytes(crypto::kSHA256Length, 0);
+      hash_->Finish(string_as_array(&hash_bytes), hash_bytes.size());
+      hashing_time_ += timer.Elapsed();
+      UMA_HISTOGRAM_TIMES("ExtensionUrlRequest.HashTimeMs", hashing_time_);
+    }
+    UMA_HISTOGRAM_COUNTS("ExtensionUrlRequest.TotalKbRead", bytes_read_ / 1024);
+    UMA_HISTOGRAM_COUNTS("ExtensionUrlRequest.SeekPosition", seek_position_);
+  }
 
   void OnFilePathAndLastModifiedTimeRead(base::FilePath* read_file_path,
                                          base::Time* last_modified_time) {
@@ -206,6 +253,18 @@ class URLRequestExtensionJob : public net::URLRequestFileJob {
     URLRequestFileJob::Start();
   }
 
+  // A hash of the contents we've read from the file.
+  scoped_ptr<crypto::SecureHash> hash_;
+
+  // The position we seeked to in the file.
+  int64 seek_position_;
+
+  // The number of bytes of content we read from the file.
+  int bytes_read_;
+
+  // Used to count the total time it takes to do hashing operations.
+  base::TimeDelta hashing_time_;
+
   net::HttpResponseInfo response_info_;
   base::FilePath directory_path_;
   extensions::ExtensionResource resource_;