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

content/browser/renderer_host/render_message_filter.cc

Index: content/browser/renderer_host/render_message_filter.cc
diff --git a/content/browser/renderer_host/render_message_filter.cc b/content/browser/renderer_host/render_message_filter.cc
index 13ce2f81908143bf29cb00cdc31c5c8253c351a2..ba36446d2a851a1ea8f83124b97721dbadb26700 100644
--- a/content/browser/renderer_host/render_message_filter.cc
+++ b/content/browser/renderer_host/render_message_filter.cc
@@ -33,6 +33,7 @@
 #include "content/browser/transition_request_manager.h"
 #include "content/common/child_process_host_impl.h"
 #include "content/common/child_process_messages.h"
+#include "content/common/content_constants_internal.h"
 #include "content/common/cookie_data.h"
 #include "content/common/desktop_notification_messages.h"
 #include "content/common/frame_messages.h"
@@ -391,6 +392,8 @@ bool RenderMessageFilter::OnMessageReceived(const IPC::Message& message) {
     IPC_MESSAGE_HANDLER_DELAY_REPLY(ViewHostMsg_LoadFont, OnLoadFont)
 #endif
     IPC_MESSAGE_HANDLER(ViewHostMsg_DownloadUrl, OnDownloadUrl)
+    IPC_MESSAGE_HANDLER(ViewHostMsg_SaveImageFromDataURL,
+                        OnSaveImageFromDataURL)
 #if defined(ENABLE_PLUGINS)
     IPC_MESSAGE_HANDLER_DELAY_REPLY(ViewHostMsg_GetPlugins, OnGetPlugins)
     IPC_MESSAGE_HANDLER(FrameHostMsg_GetPluginInfo, OnGetPluginInfo)
@@ -860,11 +863,11 @@ void RenderMessageFilter::OnGetMonitorColorProfile(std::vector<char>* profile) {
 }
 #endif
 
-void RenderMessageFilter::OnDownloadUrl(int render_view_id,
-                                        const GURL& url,
-                                        const Referrer& referrer,
-                                        const base::string16& suggested_name,
-                                        const bool use_prompt) {
+void RenderMessageFilter::DownloadUrl(int render_view_id,
+                                      const GURL& url,
+                                      const Referrer& referrer,
+                                      const base::string16& suggested_name,
+                                      const bool use_prompt) {
   scoped_ptr<DownloadSaveInfo> save_info(new DownloadSaveInfo());
   save_info->suggested_name = suggested_name;
   save_info->prompt_for_save_location = use_prompt;
@@ -893,6 +896,22 @@ void RenderMessageFilter::OnDownloadUrl(int render_view_id,
       ResourceDispatcherHostImpl::DownloadStartedCallback());
 }
 
+void RenderMessageFilter::OnDownloadUrl(int render_view_id,
+                                        const GURL& url,
+                                        const Referrer& referrer,
+                                        const base::string16& suggested_name) {
+  DownloadUrl(render_view_id, url, referrer, suggested_name);
+}
+
+void RenderMessageFilter::OnSaveImageFromDataURL(int render_view_id,
+                                                 const std::string& data_url) {
+  // Note: |data_url| has a size limitation. (< 10MiB)

[palmer, 2014/09/03 17:31:46]

Minor nit: I think the code is so clear (line 910) that this comment is
unnecessary.

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

Done.

+  // Please refer to RenderViewImpl::saveImageFromDataURL().
+  if (data_url.length() < kMaxLengthOfDataURLString)

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

Please see my comments in your other CL
https://codereview.chromium.org/518043003/ . After thinking about this more
carefully, I think that this should construct the GURL for the incoming data_url
and make sure the scheme is actually data:, returning immediately otherwise.
Then the old code path should be invoked for images, not this one. I suspect
there's a reason that images' download was initiated through ResourceRequest and
I don't think that should be changed.

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

It will be return in WebViewImpl::saveImageAt(). (if the url is not data url)
In that case, this function is not invoked.
This new path is only used by canvas or img to have large data url.

+    DownloadUrl(render_view_id, GURL(data_url),
+        Referrer(), base::string16(), true);
+}
+
 void RenderMessageFilter::OnCheckNotificationPermission(
     const GURL& source_origin, int* result) {
 #if defined(ENABLE_NOTIFICATIONS)