Don't hold pointer moves on Linux

content/browser/compositor/delegated_frame_host.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/compositor/delegated_frame_host.h"
 
 #include "base/callback_helpers.h"
 #include "base/command_line.h"
 #include "cc/output/compositor_frame.h"
 #include "cc/output/compositor_frame_ack.h"
@@ skipping 66 matching lines @@
       can_lock_compositor_ == NO_PENDING_RENDERER_FRAME ||
       can_lock_compositor_ == NO_PENDING_COMMIT;
 
   if (can_lock_compositor_ == YES_CAN_LOCK)
     can_lock_compositor_ = YES_DID_LOCK;
 
   resize_lock_ = client_->CreateResizeLock(defer_compositor_lock);
 }
 
 bool DelegatedFrameHost::ShouldCreateResizeLock() {
-  // On Windows while resizing, the the resize locks makes us mis-paint a white
-  // vertical strip (including the non-client area) if the content composition
-  // is lagging the UI composition. So here we disable the throttling so that
-  // the UI bits can draw ahead of the content thereby reducing the amount of
-  // whiteout. Because this causes the content to be drawn at wrong sizes while
-  // resizing we compensate by blocking the UI thread in Compositor::Draw() by
-  // issuing a FinishAllRendering() if we are resizing.
+  // On Windows and Linux, holding pointer moves will not help throttling
+  // resizes.
+  // TODO(piman): on Windows we need to block (nested message loop?) the
+  // WM_SIZE event. On Linux we need to throttle at the WM level using
+  // _NET_WM_SYNC_REQUEST.
   // TODO(ccameron): Mac browser window resizing is incompletely implemented.
-#if defined(OS_WIN) || defined(OS_MACOSX)
+#if !defined(OS_CHROMEOS)
   return false;
 #else
   RenderWidgetHostImpl* host = client_->GetHost();
 
   if (resize_lock_)
     return false;
 
   if (host->should_auto_resize())
     return false;
   if (!host->is_accelerated_compositing_active())
@@ skipping 763 matching lines @@
   // that should keep our frame. old_layer will be returned to the
   // RecreateLayer caller, and should have a copy.
   if (frame_provider_.get()) {
     new_layer->SetShowDelegatedContent(frame_provider_.get(),
                                        current_frame_size_in_dip_);
   }
 }
 
 }  // namespace content