Add |SetImageDownloadLimit| to ImageFetcher to limit downloaded bytes

components/image_fetcher/core/image_data_fetcher.h

Index: components/image_fetcher/core/image_data_fetcher.h
diff --git a/components/image_fetcher/core/image_data_fetcher.h b/components/image_fetcher/core/image_data_fetcher.h
index cac22fa2f581f121889c18fbcf4d3b6e508c8860..b8cf257c4b3f0e1ae9dbf0605440df9599e5acab 100644
--- a/components/image_fetcher/core/image_data_fetcher.h
+++ b/components/image_fetcher/core/image_data_fetcher.h
@@ -42,6 +42,13 @@ class ImageDataFetcher : public net::URLFetcherDelegate {
   // Sets a service name against which to track data usage.
   void SetDataUseServiceName(DataUseServiceName data_use_service_name);
 
+  // Sets an upper limit for image downloads that is by default disabled.

[Marc Treib, 2017/03/27 13:16:42]

nit: Remove "that is by default disabled", IMO that doesn't belong on the
setter.

[fhorschig, 2017/03/27 14:33:43]

Done.

+  // Setting |max_download_bytes| to a negative value will disable the limit.

[Marc Treib, 2017/03/27 13:16:42]

Hm. Make it a base::Optional<int64_t> instead? IMO that's clearer than the
negative values hack.

[fhorschig, 2017/03/27 14:33:43]

Done.

+  // Already running downloads are immediately affected.
+  void SetImageDownloadLimit(int64_t max_download_bytes) {
+    max_download_bytes_ = max_download_bytes < 0 ? 0 : max_download_bytes;

[Marc Treib, 2017/03/27 13:16:42]

Move implementation to .cc file?

[fhorschig, 2017/03/27 14:33:43]

Done.

+  }
+
   // Fetches the raw image bytes from the given |image_url| and calls the given
   // |callback|. The callback is run even if fetching the URL fails. In case
   // of an error an empty string is passed to the callback.
@@ -57,8 +64,12 @@ class ImageDataFetcher : public net::URLFetcherDelegate {
  private:
   struct ImageDataFetcherRequest;
 
-  // Method inherited from URLFetcherDelegate
+  // Methods inherited from URLFetcherDelegate
   void OnURLFetchComplete(const net::URLFetcher* source) override;
+  void OnURLFetchDownloadProgress(const net::URLFetcher* source,
+                                  int64_t current,
+                                  int64_t total,
+                                  int64_t current_network_bytes) override;
 
   // All active image url requests.
   std::map<const net::URLFetcher*, std::unique_ptr<ImageDataFetcherRequest>>
@@ -75,6 +86,10 @@ class ImageDataFetcher : public net::URLFetcherDelegate {
   // is not used.
   int next_url_fetcher_id_;
 
+  // Running requests exceeding this limit will be canceled immediately. By

[Marc Treib, 2017/03/27 13:16:42]

Upper limit for the number of bytes to download per image.
(The "running requests..." part is really secondary)

[fhorschig, 2017/03/27 14:33:43]

Done.

+  // default negative and therefore disabled.
+  int64_t max_download_bytes_;
+
   DISALLOW_COPY_AND_ASSIGN(ImageDataFetcher);
 };