Fix a crash when saving a <canvas> or <img> image which is large.

chrome/browser/renderer_context_menu/render_view_context_menu.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 "chrome/browser/renderer_context_menu/render_view_context_menu.h"
 
 #include <algorithm>
 #include <set>
 #include <utility>
 
@@ skipping 1068 matching lines @@
           ProfileIOData::IsHandledProtocol(params_.link_url.scheme());
     }
 
     case IDC_CONTENT_CONTEXT_SAVEIMAGEAS: {
       PrefService* local_state = g_browser_process->local_state();
       DCHECK(local_state);
       // Test if file-selection dialogs are forbidden by policy.
       if (!local_state->GetBoolean(prefs::kAllowFileSelectionDialogs))
         return false;
 
-      if (params_.media_type == WebContextMenuData::MediaTypeCanvas)
-        return true;
-
-      return params_.src_url.is_valid() &&
-          ProfileIOData::IsHandledProtocol(params_.src_url.scheme());
+      // If |params_.src_url| is empty, it might be a large data url.

[Avi (use Gerrit), 2014/09/03 15:21:05]

The word "might" here makes me uncomfortable. Two cases:

- If src_url is empty, does that mean that it is _always_ a large data URL? If
so, fix the comment to avoid "might".
- If src_url being empty indeed means that it might be a large data URL but
maybe not, is it worth checking? If it is, check. If not, explain in your
comment why we shouldn't.

[Ken Russell (switch to Gerrit), 2014/09/04 00:23:26]

Agree with Avi's comments; if the changes I suggest in your other CL
https://codereview.chromium.org/518043003/ are made, will that clarify this code
path?

[zino, 2014/09/05 03:47:47]

Done. It is better to use has_image_contents instead of checking url validation.

+      // In that case, we should enable the context menu and use
+      // RenderViewHost::SaveImageAt() method to save a image.
+      return params_.src_url.is_empty() ||
+          (params_.src_url.is_valid() &&
+          ProfileIOData::IsHandledProtocol(params_.src_url.scheme()));
     }
 
     // The images shown in the most visited thumbnails can't be opened or
     // searched for conventionally.
     case IDC_CONTENT_CONTEXT_OPENIMAGENEWTAB:
     case IDC_CONTENT_CONTEXT_SEARCHWEBFORIMAGE:
       return params_.src_url.is_valid() &&
           (params_.src_url.scheme() != content::kChromeUIScheme);
 
     case IDC_CONTENT_CONTEXT_COPYIMAGE:
@@ skipping 234 matching lines @@
       dl_params->set_referrer(referrer);
       dl_params->set_referrer_encoding(params_.frame_charset);
       dl_params->set_suggested_name(params_.suggested_filename);
       dl_params->set_prompt(true);
       dlm->DownloadUrl(dl_params.Pass());
       break;
     }
 
     case IDC_CONTENT_CONTEXT_SAVEAVAS:
     case IDC_CONTENT_CONTEXT_SAVEIMAGEAS: {
-      if (params_.media_type == WebContextMenuData::MediaTypeCanvas) {
+      if (params_.media_type == WebContextMenuData::MediaTypeCanvas ||
+          (params_.media_type == WebContextMenuData::MediaTypeImage &&
+          params_.src_url.is_empty())) {
         source_web_contents_->GetRenderViewHost()->SaveImageAt(
           params_.x, params_.y);
       } else {
-        // TODO(zino): We can use SaveImageAt() like a case of canvas.
         RecordDownloadSource(DOWNLOAD_INITIATED_BY_CONTEXT_MENU);
         const GURL& url = params_.src_url;
         content::Referrer referrer = CreateSaveAsReferrer(url, params_);
         source_web_contents_->SaveFrame(url, referrer);
       }
       break;
     }
 
     case IDC_CONTENT_CONTEXT_COPYLINKLOCATION:
       WriteURLToClipboard(params_.unfiltered_link_url);
@@ skipping 408 matching lines @@
   source_web_contents_->GetRenderViewHost()->
       ExecuteMediaPlayerActionAtLocation(location, action);
 }
 
 void RenderViewContextMenu::PluginActionAt(
     const gfx::Point& location,
     const WebPluginAction& action) {
   source_web_contents_->GetRenderViewHost()->
       ExecutePluginActionAtLocation(location, action);
 }