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

chrome/browser/renderer_context_menu/render_view_context_menu.cc

Index: chrome/browser/renderer_context_menu/render_view_context_menu.cc
diff --git a/chrome/browser/renderer_context_menu/render_view_context_menu.cc b/chrome/browser/renderer_context_menu/render_view_context_menu.cc
index b9cd2a9eecedfce55048cba489800e61eb14f447..73441fbd1eb71d7fe7494c4ee833c8a32a569d4d 100644
--- a/chrome/browser/renderer_context_menu/render_view_context_menu.cc
+++ b/chrome/browser/renderer_context_menu/render_view_context_menu.cc
@@ -1086,11 +1086,12 @@ bool RenderViewContextMenu::IsCommandIdEnabled(int id) const {
       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
@@ -1345,11 +1346,12 @@ void RenderViewContextMenu::ExecuteCommand(int id, int event_flags) {
 
     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_);