DevTools: fix screenshot size when emulated viewport is smaller than root view

content/browser/devtools/devtools_frame_trace_recorder.cc

 // Copyright (c) 2015 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/devtools_frame_trace_recorder.h"
 
 #include <stddef.h>
 
 #include <string>
 #include <vector>
@@ skipping 73 matching lines @@
 
 void CaptureFrame(RenderFrameHostImpl* host,
     const cc::CompositorFrameMetadata& metadata) {
   RenderWidgetHostViewBase* view =
       static_cast<RenderWidgetHostViewBase*>(host->GetView());
   if (!view)
     return;
   int current_frame_count = base::subtle::NoBarrier_Load(&frame_data_count);
   if (current_frame_count >= kMaximumFrameDataCount)
     return;
-  float scale = metadata.page_scale_factor;
-  float area = metadata.scrollable_viewport_size.GetArea();
-  if (area * scale * scale > kFrameAreaLimit)
-    scale = sqrt(kFrameAreaLimit / area);
-  gfx::Size snapshot_size(gfx::ToRoundedSize(gfx::ScaleSize(
-      metadata.scrollable_viewport_size, scale)));
+
+  gfx::Size src_size = gfx::ToCeiledSize(gfx::ScaleSize(
+      metadata.scrollable_viewport_size, metadata.page_scale_factor));
+  gfx::Size snapshot_size;
+  float area = src_size.GetArea();
+  if (area <= kFrameAreaLimit) {
+    snapshot_size = src_size;
+  } else {
+    double scale = sqrt(kFrameAreaLimit / area);
+    snapshot_size = gfx::ScaleToCeiledSize(src_size, scale);
+  }
+
   view->CopyFromCompositingSurface(
-      gfx::Rect(), snapshot_size,
+      gfx::Rect(gfx::Point(), src_size), snapshot_size,
       base::Bind(FrameCaptured, base::TimeTicks::Now()),
       kN32_SkColorType);
 }
 
 bool ScreenshotCategoryEnabled() {
   bool enabled;
   TRACE_EVENT_CATEGORY_GROUP_ENABLED(
       TRACE_DISABLED_BY_DEFAULT("devtools.screenshot"), &enabled);
   return enabled;
 }
@@ skipping 21 matching lines @@
   }
 
   bool is_new_trace;
   TRACE_EVENT_IS_NEW_TRACE(&is_new_trace);
   if (!is_new_trace && last_metadata_)
     CaptureFrame(host, *last_metadata_);
   last_metadata_.reset(new cc::CompositorFrameMetadata(frame_metadata));
 }
 
 }  // namespace content