Support embedded plugins with MimeHandlerView.

This change adds support for embedded plugins getting loaded via MimeHandlerView.
Changes:
-Changes MimeHandlerViewContainer to kick off a URL request when the content
is embedded. This is done because in that case, a URL request isn't started
automatically by the browser.
-Plumb through the original URL that is used to instantiate the plugin so that it can be loaded (as above).
-Change the extensions PluginManager to allow extensions that are associated
with a MIME type to be handlers for the file extensions which correspond with
that MIME type. This is needed because <embed>ed documents don't typically
specify a MIME type.

Currently the URL request made won't correctly be intercepted as an http stream. This change will be made in a followup CL.

BUG=303491

Review URL: https://codereview.chromium.org/701713003

Cr-Commit-Position: refs/heads/master@{#303152}

2 files changed, 9 insertions, 5 deletions

diff --git a/extensions/shell/renderer/shell_content_renderer_client.cc b/extensions/shell/renderer/shell_content_renderer_client.cc
index 3f5b17f..216eac6 100644
--- a/extensions/shell/renderer/shell_content_renderer_client.cc
+++ b/extensions/shell/renderer/shell_content_renderer_client.cc
@@ -179,11 +179,14 @@ bool ShellContentRendererClient::ShouldEnableSiteIsolationPolicy() const {
 content::BrowserPluginDelegate*
 ShellContentRendererClient::CreateBrowserPluginDelegate(
     content::RenderFrame* render_frame,
-    const std::string& mime_type) {
-  if (mime_type == content::kBrowserPluginMimeType)
+    const std::string& mime_type,
+    const GURL& original_url) {
+  if (mime_type == content::kBrowserPluginMimeType) {
     return new extensions::ExtensionsGuestViewContainer(render_frame);
-  else
-    return new extensions::MimeHandlerViewContainer(render_frame, mime_type);
+  } else {
+    return new extensions::MimeHandlerViewContainer(
+        render_frame, mime_type, original_url);
+  }
 }
 
 }  // namespace extensions
diff --git a/extensions/shell/renderer/shell_content_renderer_client.h b/extensions/shell/renderer/shell_content_renderer_client.h
index a4df9ca..6f62398 100644
--- a/extensions/shell/renderer/shell_content_renderer_client.h
+++ b/extensions/shell/renderer/shell_content_renderer_client.h
@@ -49,7 +49,8 @@ class ShellContentRendererClient : public content::ContentRendererClient {
   bool ShouldEnableSiteIsolationPolicy() const override;
   content::BrowserPluginDelegate* CreateBrowserPluginDelegate(
       content::RenderFrame* render_frame,
-      const std::string& mime_type) override;
+      const std::string& mime_type,
+      const GURL& original_url) override;
 
  private:
   scoped_ptr<ShellExtensionsClient> extensions_client_;