gin: Always specify thread affinity when posting tasks

*** Note: There is no behavior change from this patch. ***

The PostTask APIs will shortly be changed to require all tasks to explicitly
specify their thread affinity, i.e., whether the task should run on the thread
pool or a specific named thread such as a BrowserThread. This patch updates all
call sites with thread affinity annotation. We also remove the "WithTraits"
suffix to make the call sites more readable.

Before:

    // Thread pool task.
    base::PostTaskWithTraits(FROM_HERE, {...}, ...);

    // UI thread task.
    base::PostTaskWithTraits(FROM_HERE, {BrowserThread::UI, ...}, ...);

After:

    // Thread pool task.
    base::PostTask(FROM_HERE, {base::ThreadPool(), ...}, ...);

    // UI thread task.
    base::PostTask(FROM_HERE, {BrowserThread::UI, ...}, ...);

This patch was semi-automatically prepared with these steps:

    1. Patch in https://chromium-review.googlesource.com/c/chromium/src/+/1635827
       to make thread affinity a build-time requirement.
    2. Run an initial pass with a clang rewriter:
       https://chromium-review.googlesource.com/c/chromium/src/+/1635623
    3. ninja -C out/Debug | grep 'requested here' | cut -d: -f1-3 | sort | \
           uniq > errors.txt
    4. while read line; do
         f=$(echo $line | cut -d: -f 1)
         r=$(echo $line | cut -d: -f 2)
         c=$(echo $line | cut -d: -f 3)
         sed -i "${r}s/./&base::ThreadPool(),/$c" $f
       done < errors.txt
    5. GOTO 3 until build succeeds.
    6. Remove the "WithTraits" suffix from task API call sites:

       $ tools/git/mffr.py -i <(cat <<EOF
       [
         ["PostTaskWithTraits",                            "PostTask"],
         ["PostDelayedTaskWithTraits",                     "PostDelayedTask"],
         ["PostTaskWithTraitsAndReply",                    "PostTaskAndReply"],
         ["CreateTaskRunnerWithTraits",                    "CreateTaskRunner"],
         ["CreateSequencedTaskRunnerWithTraits",           "CreateSequencedTaskRunner"],
         ["CreateUpdateableSequencedTaskRunnerWithTraits", "CreateUpdateableSequencedTaskRunner"],
         ["CreateSingleThreadTaskRunnerWithTraits",        "CreateSingleThreadTaskRunner"],
         ["CreateCOMSTATaskRunnerWithTraits",              "CreateCOMSTATaskRunner"]
       ]
       EOF
       )

This CL was uploaded by git cl split.

R=rmcilroy@chromium.org

Bug: 968047
Change-Id: I300e3b43de664f0f6bdfefed21a22d886eef8f05
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1729151
Auto-Submit: Sami Kyöstilä <skyostil@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Commit-Queue: Sami Kyöstilä <skyostil@chromium.org>
Cr-Commit-Position: refs/heads/master@{#683187}

gin/v8_platform.cc

@@ -30,13 +30,13 @@ namespace {
 base::LazyInstance<V8Platform>::Leaky g_v8_platform = LAZY_INSTANCE_INITIALIZER;
 
 constexpr base::TaskTraits kLowPriorityTaskTraits = {
-    base::TaskPriority::BEST_EFFORT};
+    base::ThreadPool(), base::TaskPriority::BEST_EFFORT};
 
 constexpr base::TaskTraits kDefaultTaskTraits = {
-    base::TaskPriority::USER_VISIBLE};
+    base::ThreadPool(), base::TaskPriority::USER_VISIBLE};
 
 constexpr base::TaskTraits kBlockingTaskTraits = {
-    base::TaskPriority::USER_BLOCKING};
+    base::ThreadPool(), base::TaskPriority::USER_BLOCKING};
 
 void PrintStackTrace() {
   base::debug::StackTrace trace;
@@ -412,28 +412,27 @@ int V8Platform::NumberOfWorkerThreads() {
 }
 
 void V8Platform::CallOnWorkerThread(std::unique_ptr<v8::Task> task) {
-  base::PostTaskWithTraits(FROM_HERE, kDefaultTaskTraits,
-                           base::BindOnce(&v8::Task::Run, std::move(task)));
+  base::PostTask(FROM_HERE, kDefaultTaskTraits,
+                 base::BindOnce(&v8::Task::Run, std::move(task)));
 }
 
 void V8Platform::CallBlockingTaskOnWorkerThread(
     std::unique_ptr<v8::Task> task) {
-  base::PostTaskWithTraits(FROM_HERE, kBlockingTaskTraits,
-                           base::BindOnce(&v8::Task::Run, std::move(task)));
+  base::PostTask(FROM_HERE, kBlockingTaskTraits,
+                 base::BindOnce(&v8::Task::Run, std::move(task)));
 }
 
 void V8Platform::CallLowPriorityTaskOnWorkerThread(
     std::unique_ptr<v8::Task> task) {
-  base::PostTaskWithTraits(FROM_HERE, kLowPriorityTaskTraits,
-                           base::BindOnce(&v8::Task::Run, std::move(task)));
+  base::PostTask(FROM_HERE, kLowPriorityTaskTraits,
+                 base::BindOnce(&v8::Task::Run, std::move(task)));
 }
 
 void V8Platform::CallDelayedOnWorkerThread(std::unique_ptr<v8::Task> task,
                                            double delay_in_seconds) {
-  base::PostDelayedTaskWithTraits(
-      FROM_HERE, kDefaultTaskTraits,
-      base::BindOnce(&v8::Task::Run, std::move(task)),
-      base::TimeDelta::FromSecondsD(delay_in_seconds));
+  base::PostDelayedTask(FROM_HERE, kDefaultTaskTraits,
+                        base::BindOnce(&v8::Task::Run, std::move(task)),
+                        base::TimeDelta::FromSecondsD(delay_in_seconds));
 }
 
 void V8Platform::CallOnForegroundThread(v8::Isolate* isolate, v8::Task* task) {