Use UtilityProcessHost to patch files.

chrome/browser/component_updater/component_patcher.cc

Index: chrome/browser/component_updater/component_patcher.cc
diff --git a/chrome/browser/component_updater/component_patcher.cc b/chrome/browser/component_updater/component_patcher.cc
index 59f283aaf175801e3bf9cbe9729f297135e6a5a6..0ac0656b781bddc34a8c34fdac68be419a4cd92c 100644
--- a/chrome/browser/component_updater/component_patcher.cc
+++ b/chrome/browser/component_updater/component_patcher.cc
@@ -7,11 +7,15 @@
 #include <string>
 #include <vector>
 
+#include "base/basictypes.h"
 #include "base/file_util.h"
+#include "base/files/file_path.h"
 #include "base/json/json_file_value_serializer.h"
+#include "base/memory/weak_ptr.h"
 #include "base/values.h"
 #include "chrome/browser/component_updater/component_patcher_operation.h"
 #include "chrome/browser/component_updater/component_updater_service.h"
+#include "content/public/browser/browser_thread.h"
 
 namespace component_updater {
 
@@ -34,58 +38,85 @@ base::ListValue* ReadCommands(const base::FilePath& unpack_path) {
 
 }  // namespace
 
-// The patching support is not cross-platform at the moment.
-ComponentPatcherCrossPlatform::ComponentPatcherCrossPlatform() {}
+ComponentPatcher::ComponentPatcher(
+    const base::FilePath& input_dir,
+    const base::FilePath& unpack_dir,
+    ComponentInstaller* installer,
+    bool in_process,
+    scoped_refptr<base::SequencedTaskRunner> task_runner)
+    : input_dir_(input_dir),
+      unpack_dir_(unpack_dir),
+      installer_(installer),
+      in_process_(in_process),
+      ptr_factory_(this),
+      task_runner_(task_runner) {
+}
 
-ComponentUnpacker::Error ComponentPatcherCrossPlatform::Patch(
-    PatchType patch_type,
-    const base::FilePath& input_file,
-    const base::FilePath& patch_file,
-    const base::FilePath& output_file,
-    int* error) {
-  return ComponentUnpacker::kDeltaUnsupportedCommand;
+ComponentPatcher::~ComponentPatcher() {
 }
 
+void ComponentPatcher::Start(
+    const base::Callback<void(ComponentUnpacker::Error, int)>& callback) {
+  callback_ = callback;
+  commands_.reset(ReadCommands(input_dir_));
+  if (!commands_.get()) {
+    task_runner_->PostTask(
+        FROM_HERE,
+        base::Bind(callback_, ComponentUnpacker::kDeltaBadCommands, 0));
+  } else {
+    next_command_ = commands_->begin();
+    task_runner_->PostTask(
+        FROM_HERE,
+        base::Bind(&ComponentPatcher::PatchNextFile, GetWeakPtr()));
+  }
+}
 
-// Takes the contents of a differential component update in input_dir
-// and produces the contents of a full component update in unpack_dir
-// using input_abs_path_ files that the installer knows about.
-void DifferentialUpdatePatch(
-    const base::FilePath& input_dir,
-    const base::FilePath& unpack_dir,
-    ComponentPatcher* patcher,
-    ComponentInstaller* installer,
-    base::Callback<void(ComponentUnpacker::Error, int)> callback) {
-  int error = 0;
-  scoped_ptr<base::ListValue> commands(ReadCommands(input_dir));
-  if (!commands.get()) {
-    callback.Run(ComponentUnpacker::kDeltaBadCommands, error);
+void ComponentPatcher::PatchNextFile() {
+  if (next_command_ == commands_->end()) {
+    callback_.Run(ComponentUnpacker::kNone, 0);

[Sorin Jianu, 2014/02/03 20:57:57]

Why is this callback called directly and the ones below it are called in the
thread pool?

[waffles, 2014/02/07 01:00:59]

Done.

+    return;
+  }
+  if (!(*next_command_)->IsType(base::Value::TYPE_DICTIONARY)) {
+    task_runner_->PostTask(
+        FROM_HERE,
+        base::Bind(callback_, ComponentUnpacker::kDeltaBadCommands, 0));
     return;
   }
+  base::DictionaryValue* command_args =
+      static_cast<base::DictionaryValue*>(*next_command_);
+  current_operation_.reset(CreateDeltaUpdateOp(command_args));
+  if (!current_operation_) {
+    task_runner_->PostTask(
+        FROM_HERE,
+        base::Bind(callback_, ComponentUnpacker::kDeltaUnsupportedCommand, 0));
+    return;
+  }
+  current_operation_->Run(
+      command_args,
+      input_dir_,
+      unpack_dir_,
+      installer_,
+      in_process_,
+      base::Bind(&ComponentPatcher::DonePatchingFile, GetWeakPtr()),
+      task_runner_);
+}
 
-  for (base::ValueVector::const_iterator command = commands->begin(),
-      end = commands->end(); command != end; command++) {
-    if (!(*command)->IsType(base::Value::TYPE_DICTIONARY)) {
-      callback.Run(ComponentUnpacker::kDeltaBadCommands, error);
-      return;
-    }
-    base::DictionaryValue* command_args =
-        static_cast<base::DictionaryValue*>(*command);
-    scoped_ptr<DeltaUpdateOp> operation(CreateDeltaUpdateOp(command_args));
-    if (!operation) {
-      callback.Run(ComponentUnpacker::kDeltaUnsupportedCommand, error);
-      return;
-    }
-
-    ComponentUnpacker::Error result = operation->Run(
-        command_args, input_dir, unpack_dir, patcher, installer, &error);
-    if (result != ComponentUnpacker::kNone) {
-      callback.Run(result, error);
-      return;
-    }
+void ComponentPatcher::DonePatchingFile(ComponentUnpacker::Error error,
+                                        int extended_error) {
+  if (error != ComponentUnpacker::kNone) {
+    callback_.Run(error, extended_error);
+  } else if (next_command_ == commands_->end()) {

[Sorin Jianu, 2014/02/03 20:57:57]

This is the if statement that could be eliminated, possibly. Since PatchNextFile
does not seem to increment next_command_, and next_command_ is valid throughout
the PatchNextFile function, then it must not be at the end in this function.

[waffles, 2014/02/07 01:00:59]

Done.

+    callback_.Run(ComponentUnpacker::kNone, 0);
+  } else {
+    next_command_++;

[Sorin Jianu, 2014/02/03 20:57:57]

could use preincrement.

[waffles, 2014/02/07 01:00:59]

Done.

+    task_runner_->PostTask(
+        FROM_HERE,
+        base::Bind(&ComponentPatcher::PatchNextFile, GetWeakPtr()));
   }
+}
 
-  callback.Run(ComponentUnpacker::kNone, error);
+base::WeakPtr<ComponentPatcher> ComponentPatcher::GetWeakPtr() {
+  return ptr_factory_.GetWeakPtr();
 }
 
 }  // namespace component_updater