Web Share: Add log messages to explain errors

When navigator.share() fails with NotAllowedError, developers
may find log messages useful to understand the failures.

Change-Id: Ife338df5c8e97cc60de98ef4480d45ba8cdfa229
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2533215
Commit-Queue: Eric Willigers <ericwilligers@chromium.org>
Reviewed-by: Glen Robertson <glenrob@chromium.org>
Auto-Submit: Eric Willigers <ericwilligers@chromium.org>
Cr-Commit-Position: refs/heads/master@{#827695}

chrome/browser/webshare/chromeos/prepare_directory_task.cc

@@ -47,6 +47,8 @@ base::File::Error PrepareDirectoryTask::PrepareDirectory(
 
 void PrepareDirectoryTask::OnPrepareDirectory(base::File::Error result) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  if (result != base::File::FILE_OK)
+    VLOG(1) << "Could not create directory for shared files";
   std::move(callback_).Run((result == base::File::FILE_OK)
                                ? blink::mojom::ShareError::OK
                                : blink::mojom::ShareError::PERMISSION_DENIED);

chrome/browser/webshare/chromeos/sharesheet_client.cc

@@ -85,6 +85,8 @@ void SharesheetClient::Share(
 
   // The SharesheetClient only shows one share sheet at a time.
   if (current_share_.has_value() || !web_contents()) {
+    VLOG(1) << "Cannot share when an existing share is in progress, or after "
+               "navigating away";
     std::move(callback).Run(blink::mojom::ShareError::PERMISSION_DENIED);
     return;
   }

chrome/browser/webshare/chromeos/store_file_task.cc

@@ -109,6 +109,7 @@ void StoreFileTask::OnCalculatedSize(uint64_t total_size,
   DCHECK_EQ(total_size, expected_content_size);
 
   if (expected_content_size > available_space_) {
+    VLOG(1) << "Share too large: " << expected_content_size << " bytes";
     std::move(callback_).Run(blink::mojom::ShareError::PERMISSION_DENIED);
     return;
   }

chrome/browser/webshare/share_service_impl.cc

@@ -139,11 +139,13 @@ void ShareServiceImpl::Share(const std::string& title,
   content::WebContents* const web_contents =
       content::WebContents::FromRenderFrameHost(render_frame_host_);
   if (!web_contents) {
+    VLOG(1) << "Cannot share after navigating away";
     std::move(callback).Run(blink::mojom::ShareError::PERMISSION_DENIED);
     return;
   }
 
   if (files.size() > kMaxSharedFileCount) {
+    VLOG(1) << "Share too large: " << files.size() << " files";
     std::move(callback).Run(blink::mojom::ShareError::PERMISSION_DENIED);
     return;
   }
@@ -156,6 +158,8 @@ void ShareServiceImpl::Share(const std::string& title,
 
     if (IsDangerousFilename(file->name) ||
         IsDangerousMimeType(file->blob->content_type)) {
+      VLOG(1) << "File type is not supported: " << file->name
+              << " has mime type " << file->blob->content_type;
       std::move(callback).Run(blink::mojom::ShareError::PERMISSION_DENIED);
       return;
     }

third_party/blink/renderer/modules/webshare/navigator_share.cc

@@ -8,6 +8,7 @@
 #include <utility>
 
 #include "third_party/blink/public/common/browser_interface_broker_proxy.h"
+#include "third_party/blink/public/mojom/devtools/console_message.mojom-blink.h"
 #include "third_party/blink/public/mojom/feature_policy/feature_policy_feature.mojom-blink.h"
 #include "third_party/blink/public/platform/platform.h"
 #include "third_party/blink/renderer/bindings/modules/v8/v8_share_data.h"
@@ -207,13 +208,15 @@ ScriptPromise NavigatorShare::share(ScriptState* script_state,
     return ScriptPromise();
   }
 
+  ExecutionContext* const execution_context =
+      ExecutionContext::From(script_state);
+
   // The feature policy is currently not enforced.
   LocalDOMWindow* const window = LocalDOMWindow::From(script_state);
-  window->CountUse(
-      ExecutionContext::From(script_state)
-              ->IsFeatureEnabled(mojom::blink::FeaturePolicyFeature::kWebShare)
-          ? WebFeature::kWebSharePolicyAllow
-          : WebFeature::kWebSharePolicyDisallow);
+  window->CountUse(execution_context->IsFeatureEnabled(
+                       mojom::blink::FeaturePolicyFeature::kWebShare)
+                       ? WebFeature::kWebSharePolicyAllow
+                       : WebFeature::kWebSharePolicyDisallow);
 
   if (client_) {
     exception_state.ThrowDOMException(DOMExceptionCode::kInvalidStateError,
@@ -222,6 +225,7 @@ ScriptPromise NavigatorShare::share(ScriptState* script_state,
   }
 
   if (!LocalFrame::ConsumeTransientUserActivation(window->GetFrame())) {
+    VLOG(1) << "Share without transient activation (user gesture)";
     exception_state.ThrowDOMException(
         DOMExceptionCode::kNotAllowedError,
         "Must be handling a user gesture to perform a share request.");
@@ -257,6 +261,9 @@ ScriptPromise NavigatorShare::share(ScriptState* script_state,
 
     if (files.size() > kMaxSharedFileCount ||
         total_bytes > kMaxSharedFileBytes) {
+      execution_context->AddConsoleMessage(
+          mojom::blink::ConsoleMessageSource::kJavaScript,
+          mojom::blink::ConsoleMessageLevel::kWarning, "Share too large");
       exception_state.ThrowDOMException(DOMExceptionCode::kNotAllowedError,
                                         "Permission denied");
       return ScriptPromise();