Move download_item.h from content/public to components/download

This CL moves the DownloadItem class from content/public to components/download.
It is the ongoing effort to make download a standalone component.
To achieve this, this CL splits DownloadItem into 2 classes:
DownloadItem and DownloadItemDelegate.
The new DownloadItemDelegate class allows content layer to inject its own implementation.
This allows any classes that call into DownloadItem::GetWebContents()
and DownloadItem::GetBrowserContext() to still work

BUG=803135

Change-Id: I494164af65eb5d83f395b085bd35b896d62884d8
Reviewed-on: https://chromium-review.googlesource.com/907687
Commit-Queue: Min Qin <[email protected]>
Reviewed-by: John Abd-El-Malek <[email protected]>
Reviewed-by: Scott Violet <[email protected]>
Reviewed-by: David Trainor <[email protected]>
Reviewed-by: Bo <[email protected]>
Reviewed-by: Robert Sesek <[email protected]>
Reviewed-by: Sergey Volk <[email protected]>
Cr-Commit-Position: refs/heads/master@{#535817}
diff --git a/chrome/browser/download/download_danger_prompt.cc b/chrome/browser/download/download_danger_prompt.cc
index 9f1ade5..3c12bb191 100644
--- a/chrome/browser/download/download_danger_prompt.cc
+++ b/chrome/browser/download/download_danger_prompt.cc
@@ -12,7 +12,7 @@
 #include "chrome/browser/safe_browsing/safe_browsing_service.h"
 #include "chrome/common/safe_browsing/file_type_policies.h"
 #include "components/download/public/common/download_danger_type.h"
-#include "content/public/browser/download_item.h"
+#include "components/download/public/common/download_item.h"
 
 using safe_browsing::ClientDownloadResponse;
 using safe_browsing::ClientSafeBrowsingReportRequest;
@@ -52,7 +52,7 @@
 void DownloadDangerPrompt::SendSafeBrowsingDownloadReport(
     ClientSafeBrowsingReportRequest::ReportType report_type,
     bool did_proceed,
-    const content::DownloadItem& download) {
+    const download::DownloadItem& download) {
   safe_browsing::SafeBrowsingService* sb_service =
       g_browser_process->safe_browsing_service();
   ClientSafeBrowsingReportRequest report;
@@ -90,7 +90,7 @@
 
 void DownloadDangerPrompt::RecordDownloadDangerPrompt(
     bool did_proceed,
-    const content::DownloadItem& download) {
+    const download::DownloadItem& download) {
   int64_t file_type_uma_value =
       safe_browsing::FileTypePolicies::GetInstance()->UmaValueForFile(
           download.GetTargetFilePath());