[Offline Pages] Allow BackgroundLoader to track network bytes using prerenderer hook-in.

chrome/browser/android/offline_pages/background_loader_offliner.cc

Index: chrome/browser/android/offline_pages/background_loader_offliner.cc
diff --git a/chrome/browser/android/offline_pages/background_loader_offliner.cc b/chrome/browser/android/offline_pages/background_loader_offliner.cc
index 07b32f956610f7021e66e5f8d32a9027f553c854..ac4f9fb5e4ba43a736117b3710d3327ef637dd15 100644
--- a/chrome/browser/android/offline_pages/background_loader_offliner.cc
+++ b/chrome/browser/android/offline_pages/background_loader_offliner.cc
@@ -5,6 +5,7 @@
 #include "chrome/browser/android/offline_pages/background_loader_offliner.h"
 
 #include "base/metrics/histogram_macros.h"
+#include "base/supports_user_data.h"
 #include "base/sys_info.h"
 #include "chrome/browser/android/offline_pages/offline_page_mhtml_archiver.h"
 #include "chrome/browser/android/offline_pages/offliner_helper.h"
@@ -19,7 +20,20 @@
 namespace offline_pages {
 
 namespace {
-long kOfflinePageDelayMs = 2000;
+const long kOfflinePageDelayMs = 2000;
+const char kOfflinerDataKey[] = "offliner-key";

[Dmitry Titov, 2017/03/11 01:10:28]

An even better variant of this is to do that:

const int kOfflinerDataKey;
...
contents->SetUserData(&kOfflinerDataKey);

because the actual content of the string is not used anyways (the SetUserData
uses a void* passed in).

[chili, 2017/03/13 20:41:56]

Done. I extended WebContentsUserData, which has int key generation that's used
across the board. This is so we don't accidentally use the same key

+
+class OfflinerData : public base::SupportsUserData::Data {
+ public:
+  explicit OfflinerData(BackgroundLoaderOffliner* offliner) {
+    offliner_ = offliner;
+  }
+  BackgroundLoaderOffliner* offliner() { return offliner_; }
+
+ private:
+  BackgroundLoaderOffliner* offliner_;

[dewittj, 2017/03/11 01:05:13]

Please write a comment explaining the reason that lifetime is safe here.

[Dmitry Titov, 2017/03/11 01:10:28]

Would be nice to add a comment to describe why the raw ptr is assumed always
pointing to alive object here.

[chili, 2017/03/13 20:41:56]

Done.

[chili, 2017/03/13 20:41:56]

Done.

+};
+
 }  // namespace
 
 BackgroundLoaderOffliner::BackgroundLoaderOffliner(
@@ -32,6 +46,7 @@ BackgroundLoaderOffliner::BackgroundLoaderOffliner(
       save_state_(NONE),
       page_load_state_(SUCCESS),
       page_delay_ms_(kOfflinePageDelayMs),
+      network_bytes_(0LL),
       weak_ptr_factory_(this) {
   DCHECK(offline_page_model_);
   DCHECK(browser_context_);
@@ -39,7 +54,16 @@ BackgroundLoaderOffliner::BackgroundLoaderOffliner(
 
 BackgroundLoaderOffliner::~BackgroundLoaderOffliner() {}
 
-// TODO(dimich): Invoke progress_callback as appropriate.
+// static
+BackgroundLoaderOffliner* BackgroundLoaderOffliner::FromWebContents(
+    content::WebContents* contents) {
+  OfflinerData* data =
+      static_cast<OfflinerData*>(contents->GetUserData(kOfflinerDataKey));
+  if (data)
+    return data->offliner();
+  return nullptr;
+}
+
 bool BackgroundLoaderOffliner::LoadAndSave(
     const SavePageRequest& request,
     const CompletionCallback& completion_callback,
@@ -109,6 +133,7 @@ bool BackgroundLoaderOffliner::LoadAndSave(
   // Track copy of pending request.
   pending_request_.reset(new SavePageRequest(request));
   completion_callback_ = completion_callback;
+  progress_callback_ = progress_callback;
 
   // Listen for app foreground/background change.
   app_listener_.reset(new base::android::ApplicationStatusListener(
@@ -250,6 +275,14 @@ void BackgroundLoaderOffliner::SetPageDelayForTest(long delay_ms) {
   page_delay_ms_ = delay_ms;
 }
 
+void BackgroundLoaderOffliner::OnNetworkBytesChanged(int64_t bytes) {
+  if (pending_request_ && save_state_ != SAVING) {
+    network_bytes_ += bytes;
+    SavePageRequest request(*pending_request_.get());

[dewittj, 2017/03/13 17:38:20]

Last I remember, .get() is not required to dereference a unique ptr.

Also, there is no reason to copy the SavePageRequest in this callback, correct?

[chili, 2017/03/13 20:41:56]

Done.

+    progress_callback_.Run(request, network_bytes_);
+  }
+}
+
 void BackgroundLoaderOffliner::SavePage() {
   if (!pending_request_.get()) {
     DVLOG(1) << "Pending request was cleared during delay.";
@@ -334,6 +367,7 @@ void BackgroundLoaderOffliner::OnPageSaved(SavePageResult save_result,
 void BackgroundLoaderOffliner::ResetState() {
   pending_request_.reset();
   page_load_state_ = SUCCESS;
+  network_bytes_ = 0LL;
   // TODO(chili): Remove after RequestCoordinator can handle multiple offliners.
   // We reset the loader and observer after completion so loaders
   // will not be re-used across different requests/tries. This is a temporary
@@ -342,6 +376,9 @@ void BackgroundLoaderOffliner::ResetState() {
   loader_.reset(
       new background_loader::BackgroundLoaderContents(browser_context_));
   content::WebContentsObserver::Observe(loader_.get()->web_contents());
+  std::unique_ptr<OfflinerData> offliner_data(new OfflinerData(this));
+  loader_.get()->web_contents()->SetUserData(kOfflinerDataKey,

[dewittj, 2017/03/11 01:05:13]

nit: combine this (loader_.get()->web_contents()) and above into a single call

[chili, 2017/03/13 20:41:56]

Done.

+                                             std::move(offliner_data));
 }
 
 void BackgroundLoaderOffliner::OnApplicationStateChange(