[DevTools] Move PNG encoding from UI to worker thread.

content/browser/devtools/protocol/page_handler.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/devtools/protocol/page_handler.h"
 
 #include <string>
 
 #include "base/base64.h"
 #include "base/bind.h"
 #include "base/strings/string16.h"
 #include "base/strings/utf_string_conversions.h"
+#include "base/threading/worker_pool.h"
 #include "content/browser/devtools/protocol/color_picker.h"
 #include "content/browser/devtools/protocol/usage_and_quota_query.h"
 #include "content/browser/geolocation/geolocation_service_context.h"
 #include "content/browser/renderer_host/render_view_host_impl.h"
 #include "content/browser/renderer_host/render_widget_host_view_base.h"
 #include "content/browser/web_contents/web_contents_impl.h"
 #include "content/common/view_messages.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/javascript_dialog_manager.h"
 #include "content/public/browser/navigation_controller.h"
@@ skipping 16 matching lines @@
 namespace devtools {
 namespace page {
 
 namespace {
 
 static const char kPng[] = "png";
 static const char kJpeg[] = "jpeg";
 static int kDefaultScreenshotQuality = 80;
 static int kFrameRetryDelayMs = 100;
 static int kCaptureRetryLimit = 2;
-static int kMaxScreencastFramesInFlight = 4;
+static int kMaxScreencastFramesInFlight = 2;
 
 void QueryUsageAndQuotaCompletedOnIOThread(
     const UsageAndQuotaQuery::Callback& callback,
     scoped_refptr<QueryUsageAndQuotaResponse> response) {
   BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
                           base::Bind(callback, response));
 }
 
 void QueryUsageAndQuotaOnIOThread(
     scoped_refptr<storage::QuotaManager> quota_manager,
     const GURL& security_origin,
     const UsageAndQuotaQuery::Callback& callback) {
   new UsageAndQuotaQuery(
       quota_manager,
       security_origin,
       base::Bind(&QueryUsageAndQuotaCompletedOnIOThread,
                  callback));
 }
 
+std::string EncodeScreencastFrame(const SkBitmap& bitmap,
+                                  const std::string& format,
+                                  int quality) {
+  std::vector<unsigned char> data;
+  SkAutoLockPixels lock_image(bitmap);
+  bool encoded;
+  if (format == kPng) {
+    encoded = gfx::PNGCodec::Encode(
+        reinterpret_cast<unsigned char*>(bitmap.getAddr32(0, 0)),
+        gfx::PNGCodec::FORMAT_SkBitmap,
+        gfx::Size(bitmap.width(), bitmap.height()),
+        bitmap.width() * bitmap.bytesPerPixel(),
+        false, std::vector<gfx::PNGCodec::Comment>(), &data);
+  } else if (format == kJpeg) {
+    encoded = gfx::JPEGCodec::Encode(
+        reinterpret_cast<unsigned char*>(bitmap.getAddr32(0, 0)),
+        gfx::JPEGCodec::FORMAT_SkBitmap,
+        bitmap.width(),
+        bitmap.height(),
+        bitmap.width() * bitmap.bytesPerPixel(),
+        quality, &data);
+  } else {
+    encoded = false;
+  }
+
+  if (!encoded)
+    return std::string();
+
+  std::string base_64_data;
+  base::Base64Encode(
+      base::StringPiece(reinterpret_cast<char*>(&data[0]), data.size()),
+      &base_64_data);
+
+  return base_64_data;
+}
+
 }  // namespace
 
 typedef DevToolsProtocolClient::Response Response;
 
 PageHandler::PageHandler()
     : enabled_(false),
       touch_emulation_enabled_(false),
       screencast_enabled_(false),
       screencast_quality_(kDefaultScreenshotQuality),
       screencast_max_width_(-1),
@@ skipping 391 matching lines @@
   gfx::Size snapshot_size_dip(gfx::ToRoundedSize(
       gfx::ScaleSize(viewport_size_dip, scale)));
 
   if (snapshot_size_dip.width() > 0 && snapshot_size_dip.height() > 0) {
     gfx::Rect viewport_bounds_dip(gfx::ToRoundedSize(viewport_size_dip));
     view->CopyFromCompositingSurface(
         viewport_bounds_dip,
         snapshot_size_dip,
         base::Bind(&PageHandler::ScreencastFrameCaptured,
                    weak_factory_.GetWeakPtr(),
-                   screencast_format_,
-                   screencast_quality_,
                    last_compositor_frame_metadata_),
         kN32_SkColorType);
   }
 }
 
 void PageHandler::ScreencastFrameCaptured(
-    const std::string& format,
-    int quality,
     const cc::CompositorFrameMetadata& metadata,
     const SkBitmap& bitmap,
     ReadbackResponse response) {
   if (response != READBACK_SUCCESS) {
     if (capture_retry_count_) {
       --capture_retry_count_;
       base::MessageLoop::current()->PostDelayedTask(
           FROM_HERE,
           base::Bind(&PageHandler::InnerSwapCompositorFrame,
                      weak_factory_.GetWeakPtr()),
           base::TimeDelta::FromMilliseconds(kFrameRetryDelayMs));
     }
     return;
   }
+  base::PostTaskAndReplyWithResult(
+      base::WorkerPool::GetTaskRunner(true).get(),
+      FROM_HERE,
+      base::Bind(&EncodeScreencastFrame,
+                 bitmap, screencast_format_, screencast_quality_),
+      base::Bind(&PageHandler::ScreencastFrameEncoded,
+                 weak_factory_.GetWeakPtr(), metadata));
+}
 
-  std::vector<unsigned char> data;
-  SkAutoLockPixels lock_image(bitmap);
-  bool encoded;
-  if (format == kPng) {
-    encoded = gfx::PNGCodec::Encode(
-        reinterpret_cast<unsigned char*>(bitmap.getAddr32(0, 0)),
-        gfx::PNGCodec::FORMAT_SkBitmap,
-        gfx::Size(bitmap.width(), bitmap.height()),
-        bitmap.width() * bitmap.bytesPerPixel(),
-        false, std::vector<gfx::PNGCodec::Comment>(), &data);
-  } else if (format == kJpeg) {
-    encoded = gfx::JPEGCodec::Encode(
-        reinterpret_cast<unsigned char*>(bitmap.getAddr32(0, 0)),
-        gfx::JPEGCodec::FORMAT_SkBitmap,
-        bitmap.width(),
-        bitmap.height(),
-        bitmap.width() * bitmap.bytesPerPixel(),
-        quality, &data);
-  } else {
-    encoded = false;
-  }
-
-  if (!encoded)
-    return;
-
-  std::string base_64_data;
-  base::Base64Encode(
-      base::StringPiece(reinterpret_cast<char*>(&data[0]), data.size()),
-      &base_64_data);
-
+void PageHandler::ScreencastFrameEncoded(
+    const cc::CompositorFrameMetadata& metadata,
+    const std::string& data) {
   // Consider metadata empty in case it has no device scale factor.
-  if (metadata.device_scale_factor == 0 || !host_)
+  if (metadata.device_scale_factor == 0 || !host_ || data.empty())
     return;
 
   RenderWidgetHostViewBase* view = static_cast<RenderWidgetHostViewBase*>(
       host_->GetView());
   if (!view)
     return;
 
   gfx::SizeF screen_size_dip = gfx::ScaleSize(
       view->GetPhysicalBackingSize(), 1 / metadata.device_scale_factor);
   scoped_refptr<ScreencastFrameMetadata> param_metadata =
       ScreencastFrameMetadata::Create()
           ->set_page_scale_factor(metadata.page_scale_factor)
           ->set_offset_top(metadata.location_bar_content_translation.y())
           ->set_device_width(screen_size_dip.width())
           ->set_device_height(screen_size_dip.height())
           ->set_scroll_offset_x(metadata.root_scroll_offset.x())
           ->set_scroll_offset_y(metadata.root_scroll_offset.y());
   client_->ScreencastFrame(ScreencastFrameParams::Create()
-      ->set_data(base_64_data)
+      ->set_data(data)
       ->set_metadata(param_metadata)
       ->set_frame_number(++screencast_frame_sent_));
 }
 
 void PageHandler::ScreenshotCaptured(
     scoped_refptr<DevToolsProtocol::Command> command,
     const unsigned char* png_data,
     size_t png_size) {
   if (!png_data || !png_size) {
     client_->SendInternalErrorResponse(command,
@@ skipping 18 matching lines @@
 
 void PageHandler::QueryUsageAndQuotaCompleted(
     scoped_refptr<DevToolsProtocol::Command> command,
     scoped_refptr<QueryUsageAndQuotaResponse> response_data) {
   client_->SendQueryUsageAndQuotaResponse(command, response_data);
 }
 
 }  // namespace page
 }  // namespace devtools
 }  // namespace content