Use DownloadManager to initiate downloads from PluginInstaller.

chrome/browser/plugins/plugin_installer.h

Index: chrome/browser/plugins/plugin_installer.h
diff --git a/chrome/browser/plugins/plugin_installer.h b/chrome/browser/plugins/plugin_installer.h
index 6cd865927b2b55401280fe1cf796f5eefff5931c..81d3447b7ddfe2e5b2aac51fcdced182ae1ccd96 100644
--- a/chrome/browser/plugins/plugin_installer.h
+++ b/chrome/browser/plugins/plugin_installer.h
@@ -5,6 +5,7 @@
 #ifndef CHROME_BROWSER_PLUGINS_PLUGIN_INSTALLER_H_
 #define CHROME_BROWSER_PLUGINS_PLUGIN_INSTALLER_H_
 
+#include "base/gtest_prod_util.h"
 #include "base/observer_list.h"
 #include "base/strings/string16.h"
 #include "base/version.h"
@@ -17,6 +18,7 @@ class PluginInstallerObserver;
 class WeakPluginInstallerObserver;
 
 namespace content {
+class DownloadManager;
 class WebContents;
 struct WebPluginInfo;
 }
@@ -52,6 +54,10 @@ class PluginInstaller : public content::DownloadItem::Observer {
                        content::WebContents* web_contents);
 
  private:
+  void StartInstallingWithDownloadManager(
+      const GURL& plugin_url,
+      content::WebContents* web_contents,
+      content::DownloadManager* download_manager);
   void DownloadStarted(content::DownloadItem* item,
                        content::DownloadInterruptReason interrupt_reason);
   void DownloadError(const std::string& msg);
@@ -62,6 +68,10 @@ class PluginInstaller : public content::DownloadItem::Observer {
   int strong_observer_count_;
   ObserverList<WeakPluginInstallerObserver> weak_observers_;
 
+  FRIEND_TEST_ALL_PREFIXES(PluginInstallerTest,
+                           StartInstalling_SuccessfulDownload);
+  FRIEND_TEST_ALL_PREFIXES(PluginInstallerTest, StartInstalling_FailedStart);
+  FRIEND_TEST_ALL_PREFIXES(PluginInstallerTest, StartInstalling_Interrupted);
   DISALLOW_COPY_AND_ASSIGN(PluginInstaller);
 };