Improve <webview> autosize:

content/renderer/browser_plugin/browser_plugin.cc

 // Copyright 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/renderer/browser_plugin/browser_plugin.h"
 
 #include "base/command_line.h"
 #include "base/json/json_string_value_serializer.h"
 #include "base/message_loop/message_loop.h"
 #include "base/strings/string_number_conversions.h"
@@ skipping 303 matching lines @@
   // If we haven't yet heard back from the guest about the last resize request,
   // then we don't issue another request until we do in
   // BrowserPlugin::UpdateRect.
   if (!HasGuestInstanceID() || !resize_ack_received_)
     return;
   BrowserPluginHostMsg_AutoSize_Params auto_size_params;
   BrowserPluginHostMsg_ResizeGuest_Params resize_guest_params;
   if (current_auto_size) {
     GetDamageBufferWithSizeParams(&auto_size_params, &resize_guest_params);
   } else {
+    last_seen_auto_view_size_ = gfx::Size();
     GetDamageBufferWithSizeParams(NULL, &resize_guest_params);
   }
   resize_ack_received_ = false;
   browser_plugin_manager()->Send(
       new BrowserPluginHostMsg_SetAutoSize(render_view_routing_id_,
                                            guest_instance_id_,
                                            auto_size_params,
                                            resize_guest_params));
 }
 
@@ skipping 167 matching lines @@
   // In SW, |resize_ack_received_| is reset in SwapDamageBuffers().
   // In HW mode, we need to do it here so we can continue sending
   // resize messages when needed.
   if (params.is_resize_ack ||
       (!params.needs_ack && (auto_size || auto_size_ack_pending_))) {
     resize_ack_received_ = true;
   }
 
   auto_size_ack_pending_ = false;
 
-  if ((!auto_size && (width() != params.view_size.width() ||
+  bool needs_new_damage_buffer = false;
+  if (auto_size && !params.view_size.IsEmpty()) {
+    if (params.view_size.width() > last_seen_auto_view_size_.width() ||
+        params.view_size.height() > last_seen_auto_view_size_.height()) {
+      // The width or height of the view size increased, so we would need new
+      // damage buffer to hold increased pixels.
+      needs_new_damage_buffer = true;

[Fady Samuel, 2013/08/27 14:16:18]

I don't understand this fix. We set the damage buffer equal to the maximum
constraints, right? When would this happen?

[lazyboy, 2013/08/27 23:22:17]

As discussed offline, the CL changed quite a bit and we are detecting this case
via dirty flag now.

+      // A repaint is necessary to receive a UpdateRect for new size.
+      resize_guest_params.repaint = true;
+    }
+    last_seen_auto_view_size_ = params.view_size;
+  }
+
+  if (needs_new_damage_buffer ||
+      (!auto_size && (width() != params.view_size.width() ||
                       height() != params.view_size.height())) ||
       (auto_size && (!InAutoSizeBounds(params.view_size))) ||
       GetDeviceScaleFactor() != params.scale_factor) {
     // We are HW accelerated, render widget does not expect an ack,
     // but we still need to update the size.
     if (!params.needs_ack) {
       UpdateGuestAutoSizeState(auto_size);
       return;
     }
 
@@ skipping 757 matching lines @@
     const WebKit::WebMouseEvent& event) {
   browser_plugin_manager()->Send(
       new BrowserPluginHostMsg_HandleInputEvent(render_view_routing_id_,
                                                 guest_instance_id_,
                                                 plugin_rect_,
                                                 &event));
   return true;
 }
 
 }  // namespace content