Allow data URLs to trigger downloads, as they do in Firefox.

Unfortunately, many of our tests rely on being able to use WebURLLoader to load
data: URLs when there is no ResourceLoaderBridge implementation.  In those tests,
we would crash if we try to use the ResourceLoaderBridge.  To workaround that,
and because it probably a good optimization anyways, I decided to check if the
data URL has a supported MIME type, and if it does, then I let it load directly
as before.

Since data URLs may be very large, I modified DataURL::Parse to skip parsing the
'data' section of the URL if the corresponding out param is null.

R=tony
BUG=38546
TEST=none (I would like to add a download test, but they are all disabled or flaky.)

Review URL: http://codereview.chromium.org/5542001

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@68212 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 27 insertions, 1 deletions

diff --git a/webkit/glue/weburlloader_impl.cc b/webkit/glue/weburlloader_impl.cc
index a7f219d..d134382 100644
--- a/webkit/glue/weburlloader_impl.cc
+++ b/webkit/glue/weburlloader_impl.cc
@@ -14,6 +14,7 @@
 #include "base/time.h"
 #include "net/base/data_url.h"
 #include "net/base/load_flags.h"
+#include "net/base/mime_util.h"
 #include "net/base/net_errors.h"
 #include "net/base/net_util.h"
 #include "net/http/http_response_headers.h"
@@ -302,6 +303,8 @@ class WebURLLoaderImpl::Context : public base::RefCounted<Context>,
   friend class base::RefCounted<Context>;
   ~Context() {}
 
+  // We can optimize the handling of data URLs in most cases.
+  bool CanHandleDataURL(const GURL& url) const;
   void HandleDataURL();
 
   WebURLLoaderImpl* loader_;
@@ -350,7 +353,7 @@ void WebURLLoaderImpl::Context::Start(
   request_ = request;  // Save the request.
 
   GURL url = request.url();
-  if (url.SchemeIs("data")) {
+  if (url.SchemeIs("data") && CanHandleDataURL(url)) {
     if (sync_load_response) {
       // This is a sync load. Do the work now.
       sync_load_response->url = url;
@@ -662,6 +665,29 @@ void WebURLLoaderImpl::Context::OnCompletedRequest(
   Release();
 }
 
+bool WebURLLoaderImpl::Context::CanHandleDataURL(const GURL& url) const {
+  DCHECK(url.SchemeIs("data"));
+
+  // Optimize for the case where we can handle a data URL locally.  We must
+  // skip this for data URLs targetted at frames since those could trigger a
+  // download.
+  //
+  // NOTE: We special case MIME types we can render both for performance
+  // reasons as well as to support unit tests, which do not have an underlying
+  // ResourceLoaderBridge implementation.
+
+  if (request_.targetType() != WebURLRequest::TargetIsMainFrame &&
+      request_.targetType() != WebURLRequest::TargetIsSubframe)
+    return true;
+
+  std::string mime_type, unused_charset;
+  if (net::DataURL::Parse(url, &mime_type, &unused_charset, NULL) &&
+      net::IsSupportedMimeType(mime_type))
+    return true;
+
+  return false;
+}
+
 void WebURLLoaderImpl::Context::HandleDataURL() {
   ResourceResponseInfo info;
   URLRequestStatus status;