Adding a command-line flag to set MHTML generation options.

content/browser/download/save_package.cc

Index: content/browser/download/save_package.cc
diff --git a/content/browser/download/save_package.cc b/content/browser/download/save_package.cc
index 7704eb4aae239d3bb53cf152caedcd28912f8e29..1f1859c20fbe51edc28769d602c42f9907588646 100644
--- a/content/browser/download/save_package.cc
+++ b/content/browser/download/save_package.cc
@@ -8,6 +8,7 @@
 #include <utility>
 
 #include "base/bind.h"
+#include "base/command_line.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/i18n/file_util_icu.h"
@@ -48,6 +49,7 @@
 #include "content/public/browser/render_frame_host.h"
 #include "content/public/browser/resource_context.h"
 #include "content/public/browser/web_contents.h"
+#include "content/public/common/content_switches.h"
 #include "content/public/common/mhtml_generation_params.h"
 #include "net/base/filename_util.h"
 #include "net/base/io_buffer.h"
@@ -340,6 +342,22 @@ void SavePackage::InitWithDownloadItem(
     GetSavableResourceLinks();
   } else if (save_type_ == SAVE_PAGE_TYPE_AS_MHTML) {
     MHTMLGenerationParams mhtml_generation_params(saved_main_file_path_);
+
+    // Check which variant of MHTML generation is required.
+    std::string MHTMLGeneratorOptionFlag =

[dewittj, 2016/05/24 23:03:20]

Another option would be to override the default in MHTMLGenerationManager, which
would then apply to extension API as well...

+        base::CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
+        switches::kMHTMLGeneratorOption);
+
+    if (MHTMLGeneratorOptionFlag == "skip_nostore_main") {

[dewittj, 2016/05/24 23:03:20]

hm, wish this could be a constant that's shared in the about_flags.cc as well.

+      mhtml_generation_params.cache_control_policy =
+          blink::WebFrameSerializerCacheControlPolicy::
+          FailForNoStoreMainFrame;
+    } else if (MHTMLGeneratorOptionFlag == "skip_nostore_all") {
+      mhtml_generation_params.cache_control_policy =
+          blink::WebFrameSerializerCacheControlPolicy::
+          SkipAnyFrameOrResourceMarkedNoStore;
+    }
+
     web_contents()->GenerateMHTML(
         mhtml_generation_params,
         base::Bind(&SavePackage::OnMHTMLGenerated, this));