Avoid sending empty OnRepaint msgs and propagate window damage correctly

content/browser/renderer_host/render_widget_host_impl.cc

 // Copyright (c) 2012 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/renderer_host/render_widget_host_impl.h"
 
 #include <math.h>
 #include <utility>
 
 #include "base/auto_reset.h"
@@ skipping 256 matching lines @@
 }
 
 void RenderWidgetHostImpl::CompositingSurfaceUpdated() {
   GpuSurfaceTracker::Get()->SetSurfaceHandle(
       surface_id_, GetCompositingSurface());
   process_->SurfaceUpdated(surface_id_);
 }
 
 void RenderWidgetHostImpl::ResetSizeAndRepaintPendingFlags() {
   resize_ack_pending_ = false;
+  if (repaint_ack_pending_) {
+    TRACE_EVENT_ASYNC_END0(
+        "renderer_host", "RenderWidgetHostImpl::repaint_ack_pending_", this);
+  }
   repaint_ack_pending_ = false;
   in_flight_size_.SetSize(0, 0);
 }
 
 void RenderWidgetHostImpl::SendScreenRects() {
   if (!renderer_initialized_ || waiting_for_screen_rects_ack_)
     return;
 
   if (is_hidden_) {
     // On GTK, this comes in for backgrounded tabs. Ignore, to match what
@@ skipping 405 matching lines @@
   // We might have a cached backing store that we can reuse!
   BackingStore* backing_store = NULL;
   if (TryGetBackingStore(view_size, &backing_store) || !force_create)
     return backing_store;
 
   // We do not have a suitable backing store in the cache, so send out a
   // request to the renderer to paint the view if required.
   if (!repaint_ack_pending_ && !resize_ack_pending_ && !view_being_painted_) {
     repaint_start_time_ = TimeTicks::Now();
     repaint_ack_pending_ = true;
+    TRACE_EVENT_ASYNC_BEGIN0(
+        "renderer_host", "RenderWidgetHostImpl::repaint_ack_pending_", this);
     Send(new ViewMsg_Repaint(routing_id_, view_size));
   }
 
   TimeDelta max_delay = TimeDelta::FromMilliseconds(kPaintMsgTimeoutMS);
   TimeTicks end_time = TimeTicks::Now() + max_delay;
   do {
     TRACE_EVENT0("renderer_host", "GetBackingStore::WaitForUpdate");
 
 #if defined(OS_MACOSX)
     view_->AboutToWaitForBackingStoreMsg();
@@ skipping 41 matching lines @@
   if (!view_)
     return NULL;
   return view_->AllocBackingStore(size);
 }
 
 void RenderWidgetHostImpl::DonePaintingToBackingStore() {
   Send(new ViewMsg_UpdateRect_ACK(GetRoutingID()));
 }
 
 void RenderWidgetHostImpl::ScheduleComposite() {
-  if (is_hidden_ || !is_accelerated_compositing_active_) {
+  if (is_hidden_ || !is_accelerated_compositing_active_ ||
+      current_size_.IsEmpty()) {
       return;
   }
 
   // Send out a request to the renderer to paint the view if required.
   if (!repaint_ack_pending_ && !resize_ack_pending_ && !view_being_painted_) {
     repaint_start_time_ = TimeTicks::Now();
     repaint_ack_pending_ = true;
+    TRACE_EVENT_ASYNC_BEGIN0(
+        "renderer_host", "RenderWidgetHostImpl::repaint_ack_pending_", this);
     Send(new ViewMsg_Repaint(routing_id_, current_size_));
   }
 }
 
 void RenderWidgetHostImpl::StartHangMonitorTimeout(TimeDelta delay) {
   if (!GetProcess()->IsGuest() && CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kDisableHangMonitor)) {
     return;
   }
 
@@ skipping 863 matching lines @@
   // that will end up reaching GetBackingStore.
   if (is_resize_ack) {
     DCHECK(resize_ack_pending_);
     resize_ack_pending_ = false;
     in_flight_size_.SetSize(0, 0);
   }
 
   bool is_repaint_ack =
       ViewHostMsg_UpdateRect_Flags::is_repaint_ack(params.flags);
   if (is_repaint_ack) {
+    DCHECK(repaint_ack_pending_);
+    TRACE_EVENT_ASYNC_END0(
+        "renderer_host", "RenderWidgetHostImpl::repaint_ack_pending_", this);
     repaint_ack_pending_ = false;
     TimeDelta delta = TimeTicks::Now() - repaint_start_time_;
     UMA_HISTOGRAM_TIMES("MPArch.RWH_RepaintDelta", delta);
   }
 
   DCHECK(!params.view_size.IsEmpty());
 
   bool was_async = false;
 
   // If this is a GPU UpdateRect, params.bitmap is invalid and dib will be NULL.
@@ skipping 488 matching lines @@
 
   bool needs_full_paint = false;
   bool scheduled_completion_callback = false;
   BackingStoreManager::PrepareBackingStore(this, view_size, bitmap, bitmap_rect,
                                            copy_rects, scale_factor,
                                            completion_callback,
                                            &needs_full_paint,
                                            &scheduled_completion_callback);
   if (needs_full_paint) {
     repaint_start_time_ = TimeTicks::Now();
+    DCHECK(!repaint_ack_pending_);
     repaint_ack_pending_ = true;
+    TRACE_EVENT_ASYNC_BEGIN0(
+        "renderer_host", "RenderWidgetHostImpl::repaint_ack_pending_", this);
     Send(new ViewMsg_Repaint(routing_id_, view_size));
   }
 
   return scheduled_completion_callback;
 }
 
 void RenderWidgetHostImpl::ScrollBackingStoreRect(const gfx::Vector2d& delta,
                                                   const gfx::Rect& clip_rect,
                                                   const gfx::Size& view_size) {
   if (is_hidden_) {
@@ skipping 292 matching lines @@
     return;
 
   OnRenderAutoResized(new_size);
 }
 
 void RenderWidgetHostImpl::DetachDelegate() {
   delegate_ = NULL;
 }
 
 }  // namespace content