Adds window position save/restore support for multiple monitors on Mac.

Fixes a bug where windows would creep up the screen every time you quit/restarted.

BUG=http://crbug.com/16176
BUG=http://crbug.com/12854
TEST=Windows should save/restore in the correct location, with either a single
monitor or multiple monitors.
Review URL: http://codereview.chromium.org/155647

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@20911 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 59 insertions, 18 deletions

diff --git a/chrome/browser/cocoa/browser_window_controller.mm b/chrome/browser/cocoa/browser_window_controller.mm
index 7115e1f..f43724c 100644
--- a/chrome/browser/cocoa/browser_window_controller.mm
+++ b/chrome/browser/cocoa/browser_window_controller.mm
@@ -892,18 +892,13 @@ willPositionSheet:(NSWindow*)sheet
 }
 
 - (void)saveWindowPositionToPrefs:(PrefService*)prefs {
-  // Window placements are stored relative to the work area bounds,
-  // not the monitor bounds.
-  NSRect workFrame = [[[self window] screen] visibleFrame];
+  // Window positions are stored relative to the origin of the primary monitor.
+  NSRect monitorFrame = [[[NSScreen screens] objectAtIndex:0] frame];
 
   // Start with the window's frame, which is in virtual coordinates.
-  // Subtract the origin of the visibleFrame to get the window frame
-  // relative to the work area.
-  gfx::Rect bounds(NSRectToCGRect([[self window] frame]));
-  bounds.Offset(-workFrame.origin.x, -workFrame.origin.y);
-
   // Do some y twiddling to flip the coordinate system.
-  bounds.set_y(workFrame.size.height - bounds.y() - bounds.height());
+  gfx::Rect bounds(NSRectToCGRect([[self window] frame]));
+  bounds.set_y(monitorFrame.size.height - bounds.y() - bounds.height());
 
   DictionaryValue* windowPreferences = prefs->GetMutableDictionary(
       browser_->GetWindowPlacementKey().c_str());
diff --git a/chrome/browser/window_sizer_mac.mm b/chrome/browser/window_sizer_mac.mm
index ccfc627..aa91211 100644
--- a/chrome/browser/window_sizer_mac.mm
+++ b/chrome/browser/window_sizer_mac.mm
@@ -40,26 +40,72 @@ class DefaultMonitorInfoProvider : public WindowSizer::MonitorInfoProvider {
 
   virtual gfx::Rect GetMonitorWorkAreaMatching(
       const gfx::Rect& match_rect) const {
-    // TODO(rohitrao): Support multiple monitors.
-    return GetPrimaryMonitorWorkArea();
+    NSScreen* match_screen = GetMatchingScreen(match_rect);
+    return ConvertCoordinateSystem([match_screen visibleFrame]);
   }
 
   virtual gfx::Point GetBoundsOffsetMatching(
       const gfx::Rect& match_rect) const {
-    // TODO(rohitrao): Support multiple monitors.
-    return GetPrimaryMonitorWorkArea().origin();
+    NSScreen* match_screen = GetMatchingScreen(match_rect);
+    gfx::Rect bounds = ConvertCoordinateSystem([match_screen frame]);
+    gfx::Rect work_area = ConvertCoordinateSystem([match_screen visibleFrame]);
+    return gfx::Point(work_area.x() - bounds.x(), work_area.y() - bounds.y());
   }
 
-  void UpdateWorkAreas() {
-    // TODO(rohitrao): Support multiple monitors.
-    work_areas_.clear();
-    work_areas_.push_back(GetPrimaryMonitorWorkArea());
-  }
+  virtual void UpdateWorkAreas();
 
  private:
+  // Returns a pointer to the screen that most closely matches the
+  // given |match_rect|.  This function currently returns the screen
+  // that contains the largest amount of |match_rect| by area.
+  NSScreen* GetMatchingScreen(const gfx::Rect& match_rect) const {
+    // Default to the monitor with the current keyboard focus, in case
+    // |match_rect| is not on any screen at all.
+    NSScreen* max_screen = [NSScreen mainScreen];
+    int max_area = 0;
+
+    for (NSScreen* screen in [NSScreen screens]) {
+      gfx::Rect monitor_area = ConvertCoordinateSystem([screen frame]);
+      gfx::Rect intersection = monitor_area.Intersect(match_rect);
+      int area = intersection.width() * intersection.height();
+      if (area > max_area) {
+        max_area = area;
+        max_screen = screen;
+      }
+    }
+
+    return max_screen;
+  }
+
+  // The lower left corner of screen 0 is always at (0, 0).  The
+  // cross-platform code expects the origin to be in the upper left,
+  // so we have to translate |ns_rect| to the new coordinate
+  // system.
+  gfx::Rect ConvertCoordinateSystem(NSRect ns_rect) const;
+
   DISALLOW_COPY_AND_ASSIGN(DefaultMonitorInfoProvider);
 };
 
+void DefaultMonitorInfoProvider::UpdateWorkAreas() {
+  work_areas_.clear();
+
+  for (NSScreen* screen in [NSScreen screens]) {
+    gfx::Rect rect = ConvertCoordinateSystem([screen visibleFrame]);
+    work_areas_.push_back(rect);
+  }
+}
+
+gfx::Rect DefaultMonitorInfoProvider::ConvertCoordinateSystem(
+    NSRect ns_rect) const {
+  // Primary monitor is defined as the monitor with the menubar,
+  // which is always at index 0.
+  NSScreen* primary_screen = [[NSScreen screens] objectAtIndex:0];
+  float primary_screen_height = [primary_screen frame].size.height;
+  gfx::Rect rect(NSRectToCGRect(ns_rect));
+  rect.set_y(primary_screen_height - rect.y() - rect.height());
+  return rect;
+}
+
 }  // namespace
 
 // static