Save As for content retrieved via POST works in most circumstances.

chrome/browser/download/download_browsertest.cc

Index: chrome/browser/download/download_browsertest.cc
diff --git a/chrome/browser/download/download_browsertest.cc b/chrome/browser/download/download_browsertest.cc
index 4759591d02d5513e70014ff1221cbbf5809462de..a8219715fbdb3ea975639181d5cc8bdb1bcf61ca 100644
--- a/chrome/browser/download/download_browsertest.cc
+++ b/chrome/browser/download/download_browsertest.cc
@@ -44,9 +44,11 @@
 #include "content/browser/download/download_persistent_store_info.h"
 #include "content/browser/net/url_request_mock_http_job.h"
 #include "content/browser/net/url_request_slow_download_job.h"
+#include "content/browser/renderer_host/render_view_host.h"
 #include "content/browser/renderer_host/resource_dispatcher_host.h"
 #include "content/public/browser/download_item.h"
 #include "content/public/browser/download_manager.h"
+#include "content/public/browser/notification_source.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/common/page_transition_types.h"
 #include "net/base/net_util.h"
@@ -1700,7 +1702,7 @@ IN_PROC_BROWSER_TEST_F(DownloadTest, DownloadUrl) {
   DownloadSaveInfo save_info;
   save_info.prompt_for_save_location = true;
   DownloadManagerForBrowser(browser())->DownloadUrl(
-      url, GURL(""), "", false, save_info, web_contents);
+      url, GURL(""), "", false, -1, save_info, web_contents);
   observer->WaitForFinished();
   EXPECT_TRUE(observer->select_file_dialog_seen());
 
@@ -1727,7 +1729,7 @@ IN_PROC_BROWSER_TEST_F(DownloadTest, DownloadUrlToPath) {
 
   DownloadTestObserver* observer(CreateWaiter(browser(), 1));
   DownloadManagerForBrowser(browser())->DownloadUrl(
-      url, GURL(""), "", false, save_info, web_contents);
+      url, GURL(""), "", false, -1, save_info, web_contents);
   observer->WaitForFinished();
 
   // Check state.
@@ -1773,3 +1775,55 @@ IN_PROC_BROWSER_TEST_F(DownloadTest, SavePageNonHTMLViaGet) {
   ASSERT_EQ(1u, download_items.size());
   ASSERT_EQ(url, download_items[0]->GetOriginalUrl());
 }
+
+IN_PROC_BROWSER_TEST_F(DownloadTest, SavePageNonHTMLViaPost) {
+  // Do initial setup.
+  ASSERT_TRUE(InitialSetup(false));
+  ASSERT_TRUE(test_server()->Start());
+  NullSelectFile(browser());
+  std::vector<DownloadItem*> download_items;
+  GetDownloads(browser(), &download_items);
+  ASSERT_TRUE(download_items.empty());
+
+  // Navigate to a form page.
+  GURL form_url = test_server()->GetURL(
+      "files/downloads/form_page_to_post.html");
+  ASSERT_TRUE(form_url.is_valid());
+  ui_test_utils::NavigateToURL(browser(), form_url);
+
+  // Submit the form. This will send a POST reqeuest, and the response is a
+  // JPEG image. The resource also has Cache-Control: no-cache set,
+  // which normally requires revalidation each time.
+  GURL jpeg_url = test_server()->GetURL("files/post/downloads/image.jpg");
+  ASSERT_TRUE(jpeg_url.is_valid());
+  WebContents* web_contents = browser()->GetSelectedWebContents();
+  ASSERT_TRUE(web_contents != NULL);
+  ui_test_utils::WindowedNotificationObserver observer(
+      content::NOTIFICATION_NAV_ENTRY_COMMITTED,
+      content::Source<content::NavigationController>(
+          &web_contents->GetController()));
+  RenderViewHost* render_view_host = web_contents->GetRenderViewHost();
+  ASSERT_TRUE(render_view_host != NULL);
+  render_view_host->ExecuteJavascriptInWebFrame(
+        string16(), ASCIIToUTF16("SubmitForm()"));
+  observer.Wait();
+  EXPECT_EQ(jpeg_url, web_contents->GetURL());
+
+  // Stop the test server, and then try to save the page. If cache validation
+  // is not bypassed then this will fail since the server is no longer
+  // reachable. This will also fail if it tries to be retrieved via "GET"
+  // rather than "POST".
+  ASSERT_TRUE(test_server()->Stop());
+  scoped_ptr<DownloadTestObserver> waiter(
+      new DownloadTestObserver(
+          DownloadManagerForBrowser(browser()), 1, DownloadItem::COMPLETE,
+          false, DownloadTestObserver::ON_DANGEROUS_DOWNLOAD_FAIL));

[Randy Smith (Not in Mondays), 2012/02/02 19:46:10]

In general, I don't consider finish_on_select_file=false a good idea; it means
if the download system gets confused and decides that it needs to prompt, the
test will time out.  Set it to true, and then assert that's not why the observer
finished.  (Yes, the infrastructure should be written so that this is the
natural thing to do :-} :-J.)

[cbentzel, 2012/02/02 19:53:06]

Actually, it does prompt in this case. I have the NullSelectFile at the top of
the test, and an EXPECT_TRUE(waiter->select_file_dialog_seen()) below. 

[Randy Smith (Not in Mondays), 2012/02/03 19:43:06]

Right, forgot about the NullSelectFile().  Thanks.

+  browser()->SavePage();
+  waiter->WaitForFinished();
+
+  // Validate that the correct file was downloaded.
+  GetDownloads(browser(), &download_items);
+  EXPECT_TRUE(waiter->select_file_dialog_seen());
+  ASSERT_EQ(1u, download_items.size());
+  ASSERT_EQ(jpeg_url, download_items[0]->GetOriginalUrl());
+}