Reland of Change extension icon load errors to warnings (patchset #2 id:300001 of https://codereview.chromium.org/1554583002/ )

Reason for revert:
this revert managed to break the tree

Original issue's description:
> Revert of Change extension icon load errors to warnings (patchset #8 id:140001 of https://codereview.chromium.org/1537473003/ )
>
> Reason for revert:
> file read from wrong thread
>
> Original issue's description:
> > Change extension icon load errors to warnings
> >
> > During the Extension parsing step, check if the icon file exists and if not, remove that entry from the dictionary.
> >
> > Keep the same check during the validation phase and don't apply the workaround to unpacked extensions. This will more strongly discourage new extensions from making this mistake.
> >
> > BUG=570249
> >
> > Committed: https://crrev.com/6e8e7d1c49657e82d0e8f2518ad463794346321b
> > Cr-Commit-Position: refs/heads/master@{#366253}
>
> TBR=rdevlin.cronin@chromium.org
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=570249
>
> Committed: https://crrev.com/36dab10ffd04f3e38285bda1e4af07a7de081a31
> Cr-Commit-Position: refs/heads/master@{#367080}

TBR=rdevlin.cronin@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=570249

Review URL: https://codereview.chromium.org/1547413002

Cr-Commit-Position: refs/heads/master@{#367081}

1 files changed, 9 insertions, 2 deletions

diff --git a/extensions/common/manifest_handler_helpers.h b/extensions/common/manifest_handler_helpers.h
index b0249c3..e1f901a 100644
--- a/extensions/common/manifest_handler_helpers.h
+++ b/extensions/common/manifest_handler_helpers.h
@@ -6,9 +6,11 @@
 #define EXTENSIONS_COMMON_MANIFEST_HANDLER_HELPERS_H_
 
 #include <string>
+#include <vector>
 
 #include "base/memory/scoped_ptr.h"
 #include "base/strings/string16.h"
+#include "extensions/common/install_warning.h"
 
 class ExtensionIconSet;
 
@@ -17,6 +19,9 @@ class DictionaryValue;
 }
 
 namespace extensions {
+
+class Extension;
+
 namespace manifest_handler_helpers {
 
 // Strips leading slashes from the file path. Returns true iff the final path is
@@ -25,8 +30,10 @@ bool NormalizeAndValidatePath(std::string* path);
 
 // Loads icon paths defined in dictionary |icons_value| into ExtensionIconSet
 // |icons|. |icons_value| is a dictionary value {icon size -> icon path}.
-// Returns success. If load fails, |error| will be set.
-bool LoadIconsFromDictionary(const base::DictionaryValue* icons_value,
+// Returns success. If load fails, |error| will be set. Non-failure warnings may
+// be added to |extension|.
+bool LoadIconsFromDictionary(Extension* extension,
+                             const base::DictionaryValue* icons_value,
                              ExtensionIconSet* icons,
                              base::string16* error);