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

chrome/browser/download/download_browsertest.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/file_path.h"
 #include "base/file_util.h"
 #include "base/memory/ref_counted.h"
 #include "base/path_service.h"
@@ skipping 26 matching lines @@
 #include "chrome/common/chrome_notification_types.h"
 #include "chrome/common/chrome_paths.h"
 #include "chrome/common/pref_names.h"
 #include "chrome/common/url_constants.h"
 #include "chrome/test/base/in_process_browser_test.h"
 #include "chrome/test/base/ui_test_utils.h"
 #include "content/browser/download/download_file_manager.h"
 #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"
 #include "testing/gtest/include/gtest/gtest.h"
 
 using content::BrowserThread;
 using content::DownloadItem;
 using content::DownloadManager;
 using content::WebContents;
 
@@ skipping 1633 matching lines @@
 
   DownloadTestObserver* observer(
     new DownloadTestObserver(
         DownloadManagerForBrowser(browser()), 1,
         DownloadItem::COMPLETE,  // Really done
         false,                   // Ignore select file.
         DownloadTestObserver::ON_DANGEROUS_DOWNLOAD_FAIL));
   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());
 
   // Check state.
   EXPECT_EQ(1, browser()->tab_count());
   ASSERT_TRUE(CheckDownload(browser(), file, file));
   CheckDownloadUI(browser(), true, true, file);
 }
 
 IN_PROC_BROWSER_TEST_F(DownloadTest, DownloadUrlToPath) {
   ASSERT_TRUE(InitialSetup(false));
   FilePath file(FILE_PATH_LITERAL("download-test1.lib"));
   GURL url(URLRequestMockHTTPJob::GetMockUrl(file));
 
   WebContents* web_contents = browser()->GetSelectedWebContents();
   ASSERT_TRUE(web_contents);
 
   ScopedTempDir other_directory;
   ASSERT_TRUE(other_directory.CreateUniqueTempDir());
   FilePath target_file_full_path
       = other_directory.path().Append(file.BaseName());
   DownloadSaveInfo save_info;
   save_info.file_path = target_file_full_path;
 
   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.
   EXPECT_EQ(1, browser()->tab_count());
   ASSERT_TRUE(CheckDownloadFullPaths(browser(),
                                      target_file_full_path,
                                      OriginFile(file)));
 
   // Temporary downloads won't be visible.
   CheckDownloadUI(browser(), false, false, file);
@@ skipping 25 matching lines @@
           false, DownloadTestObserver::ON_DANGEROUS_DOWNLOAD_FAIL));
   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(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());
+}