RESUBMIT of http://codereview.chromium.org/404025/show

Start the WebKit thread when we initialize the resource dispatcher host.

NOTE: It's very possible this will have a startup performance impact. I'm going to watch the bots after committing.

TODO: Clean up shutdown logic that exists simply because we don't know whether or not we'll ever start the WebKit thread.

TBR=darin
TEST=The WebKit thread gets spun up early in the initialization process.
BUG=24144,28364

Review URL: http://codereview.chromium.org/432007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@33063 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 41 insertions, 65 deletions

diff --git a/chrome/browser/in_process_webkit/dom_storage_dispatcher_host.cc b/chrome/browser/in_process_webkit/dom_storage_dispatcher_host.cc
index 75b9bfc..d295ce1 100644
--- a/chrome/browser/in_process_webkit/dom_storage_dispatcher_host.cc
+++ b/chrome/browser/in_process_webkit/dom_storage_dispatcher_host.cc
@@ -150,9 +150,9 @@ void DOMStorageDispatcherHost::Send(IPC::Message* message) {
 void DOMStorageDispatcherHost::OnNamespaceId(DOMStorageType storage_type,
                                              IPC::Message* reply_msg) {
   if (ChromeThread::CurrentlyOn(ChromeThread::IO)) {
-    PostTaskToWebKitThread(FROM_HERE, NewRunnableMethod(this,
-        &DOMStorageDispatcherHost::OnNamespaceId,
-        storage_type, reply_msg));
+    ChromeThread::PostTask(ChromeThread::WEBKIT, FROM_HERE, NewRunnableMethod(
+        this, &DOMStorageDispatcherHost::OnNamespaceId, storage_type,
+        reply_msg));
     return;
   }
 
@@ -170,9 +170,9 @@ void DOMStorageDispatcherHost::OnNamespaceId(DOMStorageType storage_type,
 void DOMStorageDispatcherHost::OnCloneNamespaceId(int64 namespace_id,
                                                   IPC::Message* reply_msg) {
   if (ChromeThread::CurrentlyOn(ChromeThread::IO)) {
-    PostTaskToWebKitThread(FROM_HERE, NewRunnableMethod(this,
-        &DOMStorageDispatcherHost::OnCloneNamespaceId,
-        namespace_id, reply_msg));
+    ChromeThread::PostTask(ChromeThread::WEBKIT, FROM_HERE, NewRunnableMethod(
+        this, &DOMStorageDispatcherHost::OnCloneNamespaceId, namespace_id,
+        reply_msg));
     return;
   }
 
@@ -195,9 +195,9 @@ void DOMStorageDispatcherHost::OnStorageAreaId(int64 namespace_id,
                                                const string16& origin,
                                                IPC::Message* reply_msg) {
   if (ChromeThread::CurrentlyOn(ChromeThread::IO)) {
-    PostTaskToWebKitThread(FROM_HERE, NewRunnableMethod(this,
-        &DOMStorageDispatcherHost::OnStorageAreaId,
-        namespace_id, origin, reply_msg));
+    ChromeThread::PostTask(ChromeThread::WEBKIT, FROM_HERE, NewRunnableMethod(
+        this, &DOMStorageDispatcherHost::OnStorageAreaId, namespace_id, origin,
+        reply_msg));
     return;
   }
 
@@ -219,8 +219,8 @@ void DOMStorageDispatcherHost::OnStorageAreaId(int64 namespace_id,
 void DOMStorageDispatcherHost::OnLength(int64 storage_area_id,
                                         IPC::Message* reply_msg) {
   if (ChromeThread::CurrentlyOn(ChromeThread::IO)) {
-    PostTaskToWebKitThread(FROM_HERE, NewRunnableMethod(this,
-        &DOMStorageDispatcherHost::OnLength, storage_area_id, reply_msg));
+    ChromeThread::PostTask(ChromeThread::WEBKIT, FROM_HERE, NewRunnableMethod(
+        this, &DOMStorageDispatcherHost::OnLength, storage_area_id, reply_msg));
     return;
   }
 
@@ -240,8 +240,9 @@ void DOMStorageDispatcherHost::OnLength(int64 storage_area_id,
 void DOMStorageDispatcherHost::OnKey(int64 storage_area_id, unsigned index,
                                      IPC::Message* reply_msg) {
   if (ChromeThread::CurrentlyOn(ChromeThread::IO)) {
-    PostTaskToWebKitThread(FROM_HERE, NewRunnableMethod(this,
-        &DOMStorageDispatcherHost::OnKey, storage_area_id, index, reply_msg));
+    ChromeThread::PostTask(ChromeThread::WEBKIT, FROM_HERE, NewRunnableMethod(
+        this, &DOMStorageDispatcherHost::OnKey, storage_area_id, index,
+        reply_msg));
     return;
   }
 
@@ -262,9 +263,9 @@ void DOMStorageDispatcherHost::OnGetItem(int64 storage_area_id,
                                          const string16& key,
                                          IPC::Message* reply_msg) {
   if (ChromeThread::CurrentlyOn(ChromeThread::IO)) {
-    PostTaskToWebKitThread(FROM_HERE, NewRunnableMethod(this,
-        &DOMStorageDispatcherHost::OnGetItem,
-        storage_area_id, key, reply_msg));
+    ChromeThread::PostTask(ChromeThread::WEBKIT, FROM_HERE, NewRunnableMethod(
+        this, &DOMStorageDispatcherHost::OnGetItem, storage_area_id, key,
+        reply_msg));
     return;
   }
 
@@ -285,8 +286,8 @@ void DOMStorageDispatcherHost::OnSetItem(
     int64 storage_area_id, const string16& key, const string16& value,
     const GURL& url, IPC::Message* reply_msg) {
   if (ChromeThread::CurrentlyOn(ChromeThread::IO)) {
-    PostTaskToWebKitThread(FROM_HERE, NewRunnableMethod(this,
-        &DOMStorageDispatcherHost::OnSetItem, storage_area_id, key, value,
+    ChromeThread::PostTask(ChromeThread::WEBKIT, FROM_HERE, NewRunnableMethod(
+        this, &DOMStorageDispatcherHost::OnSetItem, storage_area_id, key, value,
         url, reply_msg));
     return;
   }
@@ -309,8 +310,9 @@ void DOMStorageDispatcherHost::OnSetItem(
 void DOMStorageDispatcherHost::OnRemoveItem(
     int64 storage_area_id, const string16& key, const GURL& url) {
   if (ChromeThread::CurrentlyOn(ChromeThread::IO)) {
-    PostTaskToWebKitThread(FROM_HERE, NewRunnableMethod(this,
-        &DOMStorageDispatcherHost::OnRemoveItem, storage_area_id, key, url));
+    ChromeThread::PostTask(ChromeThread::WEBKIT, FROM_HERE, NewRunnableMethod(
+        this, &DOMStorageDispatcherHost::OnRemoveItem, storage_area_id, key,
+        url));
     return;
   }
 
@@ -328,8 +330,8 @@ void DOMStorageDispatcherHost::OnRemoveItem(
 
 void DOMStorageDispatcherHost::OnClear(int64 storage_area_id, const GURL& url) {
   if (ChromeThread::CurrentlyOn(ChromeThread::IO)) {
-    PostTaskToWebKitThread(FROM_HERE, NewRunnableMethod(this,
-        &DOMStorageDispatcherHost::OnClear, storage_area_id, url));
+    ChromeThread::PostTask(ChromeThread::WEBKIT, FROM_HERE, NewRunnableMethod(
+        this, &DOMStorageDispatcherHost::OnClear, storage_area_id, url));
     return;
   }
 
@@ -356,9 +358,3 @@ void DOMStorageDispatcherHost::OnStorageEvent(
     ++cur;
   }
 }
-
-void DOMStorageDispatcherHost::PostTaskToWebKitThread(
-    const tracked_objects::Location& from_here, Task* task) {
-  webkit_thread_->EnsureInitialized();
-  ChromeThread::PostTask(ChromeThread::WEBKIT, FROM_HERE, task);
-}
diff --git a/chrome/browser/in_process_webkit/dom_storage_dispatcher_host.h b/chrome/browser/in_process_webkit/dom_storage_dispatcher_host.h
index b99ac94..6ca2d62 100644
--- a/chrome/browser/in_process_webkit/dom_storage_dispatcher_host.h
+++ b/chrome/browser/in_process_webkit/dom_storage_dispatcher_host.h
@@ -76,10 +76,6 @@ class DOMStorageDispatcherHost
     return webkit_context_->dom_storage_context();
   }
 
-  // Posts a task to the WebKit thread, initializing it if necessary.
-  void PostTaskToWebKitThread(
-      const tracked_objects::Location& from_here, Task* task);
-
   // Use whenever there's a chance OnStorageEvent will be called.
   class ScopedStorageEventContext {
    public:
diff --git a/chrome/browser/in_process_webkit/webkit_thread.cc b/chrome/browser/in_process_webkit/webkit_thread.cc
index 6311140..c3ad81f 100644
--- a/chrome/browser/in_process_webkit/webkit_thread.cc
+++ b/chrome/browser/in_process_webkit/webkit_thread.cc
@@ -9,9 +9,7 @@
 #include "chrome/common/chrome_switches.h"
 #include "third_party/WebKit/WebKit/chromium/public/WebKit.h"
 
-// This happens on the UI thread before the IO thread has been shut down.
 WebKitThread::WebKitThread() {
-  // The thread is started lazily by InitializeThread() on the IO thread.
 }
 
 // This happens on the UI thread after the IO thread has been shut down.
@@ -23,11 +21,19 @@ WebKitThread::~WebKitThread() {
   DCHECK(!ChromeThread::CurrentlyOn(ChromeThread::WEBKIT));
 }
 
-void WebKitThread::EnsureInitialized() {
-  DCHECK(ChromeThread::CurrentlyOn(ChromeThread::IO));
-  if (webkit_thread_.get())
+void WebKitThread::Initialize() {
+  DCHECK(ChromeThread::CurrentlyOn(ChromeThread::UI));
+  DCHECK(!webkit_thread_.get());
+
+  if (CommandLine::ForCurrentProcess()->HasSwitch(switches::kSingleProcess)) {
+    // TODO(jorlow): This thread should be used (and started) in single process
+    //               mode rather than following different code paths.
     return;
-  InitializeThread();
+  }
+
+  webkit_thread_.reset(new InternalWebKitThread);
+  bool started = webkit_thread_->Start();
+  DCHECK(started);
 }
 
 WebKitThread::InternalWebKitThread::InternalWebKitThread()
@@ -43,21 +49,10 @@ void WebKitThread::InternalWebKitThread::Init() {
   webkit_client_.reset(new BrowserWebKitClientImpl);
   WebKit::initialize(webkit_client_.get());
   // If possible, post initialization tasks to this thread (rather than doing
-  // them now) so we don't block the IO thread any longer than we have to.
+  // them now) so we don't block the UI thread any longer than we have to.
 }
 
 void WebKitThread::InternalWebKitThread::CleanUp() {
   DCHECK(webkit_client_.get());
   WebKit::shutdown();
 }
-
-MessageLoop* WebKitThread::InitializeThread() {
-  if (CommandLine::ForCurrentProcess()->HasSwitch(switches::kSingleProcess))
-    return NULL;
-
-  DCHECK(!webkit_thread_.get());
-  webkit_thread_.reset(new InternalWebKitThread);
-  bool started = webkit_thread_->Start();
-  DCHECK(started);
-  return webkit_thread_->message_loop();
-}
diff --git a/chrome/browser/in_process_webkit/webkit_thread.h b/chrome/browser/in_process_webkit/webkit_thread.h
index 97b1856..9838730 100644
--- a/chrome/browser/in_process_webkit/webkit_thread.h
+++ b/chrome/browser/in_process_webkit/webkit_thread.h
@@ -14,20 +14,14 @@
 
 class BrowserWebKitClientImpl;
 
-// This is an object that represents WebKit's "main" thread within the browser
-// process.  It should be instantiated and destroyed on the UI thread
-// before/after the IO thread is created/destroyed.  All other usage should be
-// on the IO thread.  If the browser is being run in --single-process mode, a
-// thread will never be spun up.
+// This creates a WebKit main thread on instantiation (if not in
+// --single-process mode) on construction and kills it on deletion.
 class WebKitThread {
  public:
   // Called from the UI thread.
   WebKitThread();
   ~WebKitThread();
-
-  // Creates the WebKit thread if it hasn't been already created.  Only call
-  // from the IO thread.  Only do fast-path work here.
-  void EnsureInitialized();
+  void Initialize();
 
  private:
   // Must be private so that we can carefully control its lifetime.
@@ -45,12 +39,7 @@ class WebKitThread {
     scoped_ptr<BrowserWebKitClientImpl> webkit_client_;
   };
 
-  // Returns the WebKit thread's message loop or NULL if we're in
-  // --single-process mode.  Do slow-path initialization work here.
-  MessageLoop* InitializeThread();
-
-  // Pointer to the actual WebKitThread.  NULL if not yet started.  Only modify
-  // from the IO thread while the WebKit thread is not running.
+  // Pointer to the actual WebKitThread.
   scoped_ptr<InternalWebKitThread> webkit_thread_;
 
   DISALLOW_COPY_AND_ASSIGN(WebKitThread);