Revert 24211 - Implement a readsize throttle within the TCP socket.

Add a fieldgroup trial for testing it.

BUG=none
TEST=none

Review URL: http://codereview.chromium.org/173259

TBR=mbelshe@google.com

Review URL: http://codereview.chromium.org/192027

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@25510 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 1 insertions, 52 deletions

diff --git a/chrome/renderer/render_view.cc b/chrome/renderer/render_view.cc
index d67e818..f2ae0c6 100644
--- a/chrome/renderer/render_view.cc
+++ b/chrome/renderer/render_view.cc
@@ -3313,16 +3313,6 @@ void RenderView::DumpLoadHistograms() const {
         finish - start, kBeginToFinishMin,
         kBeginToFinishMax, kBeginToFinishBucketCount);
 
-  static bool use_async_tcp(FieldTrialList::Find("AsyncSlowStart") &&
-      !FieldTrialList::Find("AsyncSlowStart")->group_name().empty());
-  if (use_async_tcp) {
-    UMA_HISTOGRAM_CUSTOM_TIMES(
-        FieldTrial::MakeName("Renderer4.StartToFinish",
-                             "AsyncSlowStart").data(),
-        finish - start, kBeginToFinishMin,
-        kBeginToFinishMax, kBeginToFinishBucketCount);
-  }
-
   UMA_HISTOGRAM_MEDIUM_TIMES("Renderer4.CommitToFinish", finish - commit);
 
   if (!first_paint.is_null()) {
diff --git a/net/socket/tcp_client_socket_win.cc b/net/socket/tcp_client_socket_win.cc
index eeefb70..de3cac6 100644
--- a/net/socket/tcp_client_socket_win.cc
+++ b/net/socket/tcp_client_socket_win.cc
@@ -6,7 +6,6 @@
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
-#include "base/field_trial.h"  // for SlowStart trial
 #include "base/memory_debug.h"
 #include "base/string_util.h"
 #include "base/sys_info.h"
@@ -119,19 +118,6 @@ class TCPClientSocketWin::Core : public base::RefCounted<Core> {
   scoped_refptr<IOBuffer> read_iobuffer_;
   scoped_refptr<IOBuffer> write_iobuffer_;
 
-  // Throttle the read size based on our current slow start state.
-  // Returns the throttled read size.
-  int ThrottleReadSize(int size) {
-    if (!use_slow_start_throttle_)
-      return size;
-
-    if (slow_start_throttle_ < kMaxSlowStartThrottle) {
-      size = std::min(size, slow_start_throttle_);
-      slow_start_throttle_ *= 2;
-    }
-    return size;
-  }
-
  private:
   class ReadDelegate : public base::ObjectWatcher::Delegate {
    public:
@@ -170,41 +156,16 @@ class TCPClientSocketWin::Core : public base::RefCounted<Core> {
   // |write_watcher_| watches for events from Write();
   base::ObjectWatcher write_watcher_;
 
-  // When doing reads from the socket, we try to mirror TCP's slow start.
-  // We do this because otherwise the async IO subsystem artifically delays
-  // returning data to the application.
-  static const int kInitialSlowStartThrottle = 1 * 1024;
-  static const int kMaxSlowStartThrottle = 32 * kInitialSlowStartThrottle;
-  int slow_start_throttle_;
-
-  static bool use_slow_start_throttle_;
-  static bool trial_initialized_;
-
   DISALLOW_COPY_AND_ASSIGN(Core);
 };
 
-bool TCPClientSocketWin::Core::use_slow_start_throttle_ = true;
-bool TCPClientSocketWin::Core::trial_initialized_ = false;
-
 TCPClientSocketWin::Core::Core(
     TCPClientSocketWin* socket)
     : socket_(socket),
       ALLOW_THIS_IN_INITIALIZER_LIST(reader_(this)),
-      ALLOW_THIS_IN_INITIALIZER_LIST(writer_(this)),
-      slow_start_throttle_(kInitialSlowStartThrottle) {
+      ALLOW_THIS_IN_INITIALIZER_LIST(writer_(this)) {
   memset(&read_overlapped_, 0, sizeof(read_overlapped_));
   memset(&write_overlapped_, 0, sizeof(write_overlapped_));
-
-  // Initialize the AsyncSlowStart FieldTrial.
-  if (!trial_initialized_) {
-    trial_initialized_ = true;
-    scoped_refptr<FieldTrial> trial = new FieldTrial("AsyncSlowStart", 100);
-    int my_group = trial->AppendGroup("_AsyncSlowStart", 50);
-    trial->AppendGroup("_AsyncSlowStart_off", 50);
-
-    // Only use the throttling if the FieldTrial is enabled.
-    use_slow_start_throttle_ = trial->group() == my_group;
-  }
 }
 
 TCPClientSocketWin::Core::~Core() {
@@ -405,8 +366,6 @@ int TCPClientSocketWin::Read(IOBuffer* buf,
   DCHECK(!read_callback_);
   DCHECK(!core_->read_iobuffer_);
 
-  buf_len = core_->ThrottleReadSize(buf_len);
-
   core_->read_buffer_.len = buf_len;
   core_->read_buffer_.buf = buf->data();