Increase image download size in AccountFetcherService

...from 64 to 256.
This is needed for the identity image in the profile menu.

Follow-up work:
Update logic to not download the same account image twice
(check whether the parameterized image URL changes).

Bug: 995720
Change-Id: I013124e784b0916c4fcfa70423061dba957c6869
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1831868
Auto-Submit: Thomas Tangl <tangltom@chromium.org>
Reviewed-by: Mihai Sardarescu <msarda@chromium.org>
Commit-Queue: Thomas Tangl <tangltom@chromium.org>
Cr-Commit-Position: refs/heads/master@{#701505}

components/signin/internal/identity_manager/account_fetcher_service.cc

@@ -50,7 +50,7 @@ const char kImageFetcherUmaClient[] = "AccountFetcherService";
 const char AccountFetcherService::kLastUpdatePref[] =
     "account_tracker_service_last_update";
 
-const int AccountFetcherService::kAccountImageDownloadSize = 64;
+const int AccountFetcherService::kAccountImageDownloadSize = 256;
 
 // AccountFetcherService implementation
 AccountFetcherService::AccountFetcherService() = default;