[fsp] Implement the chrome.fileSystemProvider.get() method.

Providing extensions may want to get file system information for the specific
file system. This CL adds such feature.

TEST=browser_tests: *FileSystemProvider*GetAll*
BUG=449014

Review URL: https://codereview.chromium.org/856433003

Cr-Commit-Position: refs/heads/master@{#312058}

6 files changed, 88 insertions, 21 deletions

diff --git a/chrome/browser/chromeos/extensions/file_system_provider/file_system_provider_api.cc b/chrome/browser/chromeos/extensions/file_system_provider/file_system_provider_api.cc
index 8a6f3b8..00909bb 100644
--- a/chrome/browser/chromeos/extensions/file_system_provider/file_system_provider_api.cc
+++ b/chrome/browser/chromeos/extensions/file_system_provider/file_system_provider_api.cc
@@ -25,6 +25,7 @@ using chromeos::file_system_provider::ProvidedFileSystemInterface;
 using chromeos::file_system_provider::ProvidedFileSystemObserver;
 using chromeos::file_system_provider::RequestValue;
 using chromeos::file_system_provider::Service;
+using chromeos::file_system_provider::Watchers;
 
 namespace extensions {
 namespace {
@@ -68,6 +69,31 @@ scoped_ptr<ProvidedFileSystemObserver::Changes> ParseChanges(
   return results;
 }
 
+// Fills the IDL's FileSystemInfo with FSP's ProvidedFileSystemInfo and
+// Watchers.
+void FillFileSystemInfo(const ProvidedFileSystemInfo& file_system_info,
+                        const Watchers& watchers,
+                        api::file_system_provider::FileSystemInfo* output) {
+  using api::file_system_provider::Watcher;
+
+  output->file_system_id = file_system_info.file_system_id();
+  output->display_name = file_system_info.display_name();
+  output->writable = file_system_info.writable();
+  output->opened_files_limit = file_system_info.opened_files_limit();
+
+  std::vector<linked_ptr<Watcher>> watcher_items;
+  for (const auto& watcher : watchers) {
+    const linked_ptr<Watcher> watcher_item(new Watcher);
+    watcher_item->entry_path = watcher.second.entry_path.value();
+    watcher_item->recursive = watcher.second.recursive;
+    if (!watcher.second.last_tag.empty())
+      watcher_item->last_tag.reset(new std::string(watcher.second.last_tag));
+    watcher_items.push_back(watcher_item);
+  }
+
+  output->watchers = watcher_items;
+}
+
 }  // namespace
 
 bool FileSystemProviderMountFunction::RunSync() {
@@ -137,7 +163,6 @@ bool FileSystemProviderUnmountFunction::RunSync() {
 
 bool FileSystemProviderGetAllFunction::RunSync() {
   using api::file_system_provider::FileSystemInfo;
-  using api::file_system_provider::Watcher;
   Service* const service = Service::Get(GetProfile());
   DCHECK(service);
 
@@ -148,10 +173,6 @@ bool FileSystemProviderGetAllFunction::RunSync() {
   for (const auto& file_system_info : file_systems) {
     if (file_system_info.extension_id() == extension_id()) {
       const linked_ptr<FileSystemInfo> item(new FileSystemInfo);
-      item->file_system_id = file_system_info.file_system_id();
-      item->display_name = file_system_info.display_name();
-      item->writable = file_system_info.writable();
-      item->opened_files_limit = file_system_info.opened_files_limit();
 
       chromeos::file_system_provider::ProvidedFileSystemInterface* const
           file_system =
@@ -159,22 +180,8 @@ bool FileSystemProviderGetAllFunction::RunSync() {
                                              file_system_info.file_system_id());
       DCHECK(file_system);
 
-      std::vector<linked_ptr<Watcher>> watcher_items;
-      chromeos::file_system_provider::Watchers* const watchers =
-          file_system->GetWatchers();
-      DCHECK(watchers);
-
-      for (const auto& watcher : *watchers) {
-        const linked_ptr<Watcher> watcher_item(new Watcher);
-        watcher_item->entry_path = watcher.second.entry_path.value();
-        watcher_item->recursive = watcher.second.recursive;
-        if (!watcher.second.last_tag.empty())
-          watcher_item->last_tag.reset(
-              new std::string(watcher.second.last_tag));
-        watcher_items.push_back(watcher_item);
-      }
-
-      item->watchers = watcher_items;
+      FillFileSystemInfo(file_system_info, *file_system->GetWatchers(),
+                         item.get());
       items.push_back(item);
     }
   }
@@ -183,6 +190,32 @@ bool FileSystemProviderGetAllFunction::RunSync() {
   return true;
 }
 
+bool FileSystemProviderGetFunction::RunSync() {
+  using api::file_system_provider::Get::Params;
+  scoped_ptr<Params> params(Params::Create(*args_));
+  EXTENSION_FUNCTION_VALIDATE(params);
+
+  using api::file_system_provider::FileSystemInfo;
+  Service* const service = Service::Get(GetProfile());
+  DCHECK(service);
+
+  chromeos::file_system_provider::ProvidedFileSystemInterface* const
+      file_system = service->GetProvidedFileSystem(extension_id(),
+                                                   params->file_system_id);
+
+  if (!file_system) {
+    SetError(FileErrorToString(base::File::FILE_ERROR_NOT_FOUND));
+    return false;
+  }
+
+  FileSystemInfo file_system_info;
+  FillFileSystemInfo(file_system->GetFileSystemInfo(),
+                     *file_system->GetWatchers(), &file_system_info);
+  SetResultList(
+      api::file_system_provider::Get::Results::Create(file_system_info));
+  return true;
+}
+
 bool FileSystemProviderNotifyFunction::RunAsync() {
   using api::file_system_provider::Notify::Params;
   scoped_ptr<Params> params(Params::Create(*args_));
diff --git a/chrome/browser/chromeos/extensions/file_system_provider/file_system_provider_api.h b/chrome/browser/chromeos/extensions/file_system_provider/file_system_provider_api.h
index 22f43b7..592bb6e 100644
--- a/chrome/browser/chromeos/extensions/file_system_provider/file_system_provider_api.h
+++ b/chrome/browser/chromeos/extensions/file_system_provider/file_system_provider_api.h
@@ -40,6 +40,15 @@ class FileSystemProviderGetAllFunction : public ChromeSyncExtensionFunction {
   bool RunSync() override;
 };
 
+class FileSystemProviderGetFunction : public ChromeSyncExtensionFunction {
+ public:
+  DECLARE_EXTENSION_FUNCTION("fileSystemProvider.get", FILESYSTEMPROVIDER_GET)
+
+ protected:
+  ~FileSystemProviderGetFunction() override {}
+  virtual bool RunSync() override;
+};
+
 class FileSystemProviderNotifyFunction : public ChromeAsyncExtensionFunction {
  public:
   DECLARE_EXTENSION_FUNCTION("fileSystemProvider.notify",
diff --git a/chrome/common/extensions/api/file_system_provider.idl b/chrome/common/extensions/api/file_system_provider.idl
index ca99320..b04ac0a 100644
--- a/chrome/common/extensions/api/file_system_provider.idl
+++ b/chrome/common/extensions/api/file_system_provider.idl
@@ -397,6 +397,9 @@ namespace fileSystemProvider {
   // Callback to receive the result of getAll() function.
   callback GetAllCallback = void(FileSystemInfo[] fileSystems);
 
+  // Callback to receive the result of get() function.
+  callback GetCallback = void(FileSystemInfo fileSystem);
+
   // Callback to be called by the providing extension in case of a success.
   [nocompile] callback ProviderSuccessCallback = void();
 
@@ -450,6 +453,10 @@ namespace fileSystemProvider {
     // Returns all file systems mounted by the extension.
     static void getAll(GetAllCallback callback);
 
+    // Returns information about a file system with the passed <code>
+    // fileSystemId</code>.
+    static void get(DOMString fileSystemId, GetCallback callback);
+
     // Notifies about changes in the watched directory at <code>
     // observedPath</code> in <code>recursive</code mode. If the file system is
     // mounted with <code>supportsNofityTag</code>, then <code>tag</code> must
diff --git a/chrome/test/data/extensions/api_test/file_system_provider/get_all/test.js b/chrome/test/data/extensions/api_test/file_system_provider/get_all/test.js
index ae1036d..d9e84dc 100644
--- a/chrome/test/data/extensions/api_test/file_system_provider/get_all/test.js
+++ b/chrome/test/data/extensions/api_test/file_system_provider/get_all/test.js
@@ -28,6 +28,16 @@ chrome.test.runTests([
                 chrome.test.assertTrue(fileSystems[0].writable);
                 chrome.test.assertEq(2, fileSystems[0].openedFilesLimit);
               }));
+          chrome.fileSystemProvider.get(
+              test_util.FILE_SYSTEM_ID,
+              chrome.test.callbackPass(function(fileSystem) {
+                chrome.test.assertEq(
+                    test_util.FILE_SYSTEM_ID, fileSystem.fileSystemId);
+                chrome.test.assertEq(
+                    test_util.FILE_SYSTEM_NAME, fileSystem.displayName);
+                chrome.test.assertTrue(fileSystem.writable);
+                chrome.test.assertEq(2, fileSystem.openedFilesLimit);
+              }));
         }));
   },
 
@@ -41,6 +51,9 @@ chrome.test.runTests([
               function(fileSystems) {
                 chrome.test.assertEq(0, fileSystems.length);
               }));
+          chrome.fileSystemProvider.get(
+              test_util.FILE_SYSTEM_ID,
+              chrome.test.callbackFail('NOT_FOUND'));
         }));
   },
 
@@ -54,6 +67,9 @@ chrome.test.runTests([
               function(fileSystems) {
                 chrome.test.assertEq(0, fileSystems.length);
               }));
+          chrome.fileSystemProvider.get(
+              test_util.FILE_SYSTEM_ID,
+              chrome.test.callbackFail('NOT_FOUND'));
         }));
   }
 ]);
diff --git a/extensions/browser/extension_function_histogram_value.h b/extensions/browser/extension_function_histogram_value.h
index 413cf77..dc9d407 100644
--- a/extensions/browser/extension_function_histogram_value.h
+++ b/extensions/browser/extension_function_histogram_value.h
@@ -1009,6 +1009,7 @@ enum HistogramValue {
   PRINTERPROVIDERINTERNAL_REPORTPRINTRESULT,
   PRINTERPROVIDERINTERNAL_REPORTPRINTERCAPABILITY,
   PRINTERPROVIDERINTERNAL_REPORTPRINTERS,
+  FILESYSTEMPROVIDER_GET,
   // Last entry: Add new entries above and ensure to update
   // tools/metrics/histograms/histograms.xml.
   ENUM_BOUNDARY
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index ce3a686..63a508b 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -46783,6 +46783,7 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   <int value="948" label="PRINTERPROVIDERINTERNAL_REPORTPRINTRESULT"/>
   <int value="949" label="PRINTERPROVIDERINTERNAL_REPORTPRINTERCAPABILITY"/>
   <int value="950" label="PRINTERPROVIDERINTERNAL_REPORTPRINTERS"/>
+  <int value="951" label="FILESYSTEMPROVIDER_GET"/>
 </enum>
 
 <enum name="ExtensionInstallCause" type="int">