[BlobAsync] Disk support for blob storage

content/browser/blob_storage/chrome_blob_storage_context.cc

Index: content/browser/blob_storage/chrome_blob_storage_context.cc
diff --git a/content/browser/blob_storage/chrome_blob_storage_context.cc b/content/browser/blob_storage/chrome_blob_storage_context.cc
index 533d3f10e222532aaa763dc26afc2df05a448995..5e751b934d277fe9edbafe87cef061f6e881fb17 100644
--- a/content/browser/blob_storage/chrome_blob_storage_context.cc
+++ b/content/browser/blob_storage/chrome_blob_storage_context.cc
@@ -7,7 +7,14 @@
 #include <utility>
 
 #include "base/bind.h"
+#include "base/files/file.h"
+#include "base/files/file_enumerator.h"
+#include "base/files/file_util.h"
 #include "base/guid.h"
+#include "base/metrics/histogram_macros.h"
+#include "base/single_thread_task_runner.h"
+#include "base/task_runner.h"
+#include "base/threading/sequenced_worker_pool.h"
 #include "content/public/browser/blob_handle.h"
 #include "content/public/browser/browser_context.h"
 #include "content/public/browser/browser_thread.h"
@@ -15,12 +22,33 @@
 #include "storage/browser/blob/blob_data_handle.h"
 #include "storage/browser/blob/blob_storage_context.h"
 
+using base::FilePath;
 using base::UserDataAdapter;
 using storage::BlobStorageContext;
 
 namespace content {
 
 namespace {
+const char kBlobStorageParentDirectory[] = "blob_storage";
+
+// Removes all folders in the parent directory except for the
+// |current_run_dir| folder. If this path is empty, then we delete all folders.
+void RemoveOldBlobStorageDirectories(FilePath blob_storage_parent,
+                                     const FilePath& current_run_dir) {
+  if (!base::DirectoryExists(blob_storage_parent)) {
+    return;
+  }
+  base::FileEnumerator enumerator(blob_storage_parent, false,
+                                  base::FileEnumerator::DIRECTORIES);
+  std::vector<std::string> components;
+  bool success = true;
+  for (base::FilePath name = enumerator.Next(); !name.empty();
+       name = enumerator.Next()) {
+    if (current_run_dir.empty() || name != current_run_dir)
+      success &= base::DeleteFile(name, true);
+  }
+  LOCAL_HISTOGRAM_BOOLEAN("Storage.Blob.CleanupSuccess", success);
+}
 
 const char kBlobStorageContextKeyName[] = "content_blob_storage_context";
 
@@ -49,11 +77,40 @@ ChromeBlobStorageContext* ChromeBlobStorageContext::GetFor(
     context->SetUserData(
         kBlobStorageContextKeyName,
         new UserDataAdapter<ChromeBlobStorageContext>(blob.get()));
-    // Check first to avoid memory leak in unittests.
-    if (BrowserThread::IsMessageLoopValid(BrowserThread::IO)) {
+
+    // Check to avoid memory leak in unittests.
+    bool io_thread_valid = BrowserThread::IsMessageLoopValid(BrowserThread::IO);
+
+    // Resolve our storage directories.
+    base::FilePath blob_storage_parent =
+        context->GetPath().Append(kBlobStorageParentDirectory);
+    base::FilePath blob_storage_dir =
+        blob_storage_parent.Append(base::GenerateGUID());
+
+    // Only populate the task runner if we're not off the record. This enables
+    // paging/saving blob data to disk.
+    scoped_refptr<base::TaskRunner> file_task_runner;
+
+    // If we're not incognito mode, schedule all of our file tasks to enable
+    // disk on the storage context.
+    if (!context->IsOffTheRecord() && io_thread_valid) {
+      file_task_runner =
+          BrowserThread::GetBlockingPool()->GetTaskRunnerWithShutdownBehavior(
+              base::SequencedWorkerPool::SKIP_ON_SHUTDOWN);
+
+      // Removes our old blob directories if they exist.
+      BrowserThread::PostAfterStartupTask(
+          FROM_HERE, file_task_runner,
+          base::Bind(&RemoveOldBlobStorageDirectories,
+                     base::Passed(&blob_storage_parent), blob_storage_dir));
+    }
+
+    if (io_thread_valid) {
       BrowserThread::PostTask(
           BrowserThread::IO, FROM_HERE,
-          base::Bind(&ChromeBlobStorageContext::InitializeOnIOThread, blob));
+          base::Bind(&ChromeBlobStorageContext::InitializeOnIOThread, blob,
+                     base::Passed(&blob_storage_dir),
+                     base::Passed(&file_task_runner)));
     }
   }
 
@@ -61,9 +118,12 @@ ChromeBlobStorageContext* ChromeBlobStorageContext::GetFor(
       context, kBlobStorageContextKeyName);
 }
 
-void ChromeBlobStorageContext::InitializeOnIOThread() {
+void ChromeBlobStorageContext::InitializeOnIOThread(
+    base::FilePath blob_storage_dir,
+    scoped_refptr<base::TaskRunner> file_task_runner) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
-  context_.reset(new BlobStorageContext());
+  context_.reset(new BlobStorageContext(std::move(blob_storage_dir),
+                                        std::move(file_task_runner)));
 }
 
 std::unique_ptr<BlobHandle> ChromeBlobStorageContext::CreateMemoryBackedBlob(