Use the asynchronous version of CopyFromBackingStore in CaptureVisibleTabFunction.

chrome/browser/extensions/extension_tabs_module.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 "chrome/browser/extensions/extension_tabs_module.h"
 
 #include <algorithm>
 #include <vector>
 
 #include "base/base64.h"
@@ skipping 39 matching lines @@
 #include "chrome/common/extensions/extension_messages.h"
 #include "chrome/common/extensions/user_script.h"
 #include "chrome/common/pref_names.h"
 #include "chrome/common/url_constants.h"
 #include "content/public/browser/navigation_controller.h"
 #include "content/public/browser/navigation_entry.h"
 #include "content/public/browser/notification_details.h"
 #include "content/public/browser/notification_source.h"
 #include "content/public/browser/render_view_host.h"
 #include "content/public/browser/render_view_host_delegate.h"
+#include "content/public/browser/render_widget_host_view.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/browser/web_contents_view.h"
 #include "content/public/common/url_constants.h"
 #include "skia/ext/image_operations.h"
 #include "skia/ext/platform_canvas.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "ui/base/ui_base_types.h"
 #include "ui/gfx/codec/jpeg_codec.h"
 #include "ui/gfx/codec/png_codec.h"
 
@@ skipping 1581 matching lines @@
 
     if (options->HasKey(keys::kQualityKey)) {
       EXTENSION_FUNCTION_VALIDATE(
           options->GetInteger(keys::kQualityKey, &image_quality_));
     }
   }
 
   // captureVisibleTab() can return an image containing sensitive information
   // that the browser would otherwise protect.  Ensure the extension has
   // permission to do this.
-  if (!GetExtension()->CanCaptureVisiblePage(web_contents->GetURL(), &error_))
+  if (!GetExtension()->CanCaptureVisiblePage(web_contents->GetURL(), &error_)) {
+    error_ = keys::kInternalVisibleTabCaptureError;

[mazda, 2012/05/03 22:24:50]

It looks we should not set error here. Adding this broke several tests.
I reverted the change of this part.

[Sam Kerner (Chrome), 2012/05/04 04:29:59]

Looks like Extension::CanCaptureVisiblePage(.., &error) sets error when it
returns false.  

     return false;
+  }
 
   RenderViewHost* render_view_host = web_contents->GetRenderViewHost();
+  content::RenderWidgetHostView* view = render_view_host->GetView();
+  if (!view) {
+    error_ = keys::kInternalVisibleTabCaptureError;
+    return false;
+  }
+  skia::PlatformCanvas* temp_canvas = new skia::PlatformCanvas;
+  render_view_host->AsyncCopyFromBackingStore(
+      gfx::Rect(),
+      view->GetViewBounds().size(),
+      temp_canvas,
+      base::Bind(&CaptureVisibleTabFunction::CopyFromBackingStoreComplete,
+                 this,
+                 base::Owned(temp_canvas)));
+  return true;
+}
 
-  // If a backing store is cached for the tab we want to capture,
-  // and it can be copied into a bitmap, then use it to generate the image.
-  // For example, some uncommon X11 visual modes are not supported by
-  // CopyFromBackingStore().
-  skia::PlatformCanvas temp_canvas;
-  if (render_view_host->CopyFromBackingStore(
-          gfx::Rect(), gfx::Size(), &temp_canvas)) {
+void CaptureVisibleTabFunction::CopyFromBackingStoreComplete(
+    skia::PlatformCanvas* canvas,
+    bool succeeded) {
+  if (succeeded) {
     VLOG(1) << "captureVisibleTab() got image from backing store.";
-    SendResultFromBitmap(skia::GetTopDevice(temp_canvas)->accessBitmap(false));
-    return true;
+    SendResultFromBitmap(skia::GetTopDevice(*canvas)->accessBitmap(false));
+    return;
+  }
+
+  WebContents* web_contents = NULL;
+  TabContentsWrapper* wrapper = NULL;
+  if (!GetTabToCapture(&web_contents, &wrapper)) {
+    error_ = keys::kInternalVisibleTabCaptureError;
+    SendResponse(false);
+    return;
   }
 
   // Ask the renderer for a snapshot of the tab.
-  wrapper->snapshot_tab_helper()->CaptureSnapshot();
   registrar_.Add(this,
                  chrome::NOTIFICATION_TAB_SNAPSHOT_TAKEN,
-                 content::Source<WebContents>(wrapper->web_contents()));
+                 content::Source<WebContents>(web_contents));
   AddRef();  // Balanced in CaptureVisibleTabFunction::Observe().
   wrapper->snapshot_tab_helper()->CaptureSnapshot();
-
-  return true;
 }
 
 // If a backing store was not available in CaptureVisibleTabFunction::RunImpl,
 // than the renderer was asked for a snapshot.  Listen for a notification
 // that the snapshot is available.
 void CaptureVisibleTabFunction::Observe(
     int type,
     const content::NotificationSource& source,
     const content::NotificationDetails& details) {
   DCHECK(type == chrome::NOTIFICATION_TAB_SNAPSHOT_TAKEN);
@@ skipping 131 matching lines @@
   // called for every API call the extension made.
   GotLanguage(language);
 }
 
 void DetectTabLanguageFunction::GotLanguage(const std::string& language) {
   result_.reset(Value::CreateStringValue(language.c_str()));
   SendResponse(true);
 
   Release();  // Balanced in Run()
 }